Idea Collector

annotated article // Hacker Noon

All things equal, additional liquidity increases the expected value from trade.

A share of stock that’s traded on an exchange is of higher value than a share of stock in an identical private company because there are less frictions to trade the public stock. Less frictions often mean more market participants, more volume, smaller spreads, and less price impact.

example: The advent of sites like eBay made life a lot better for baseball card traders because it opened up competitive markets with more participants and volume, and assets could be bought and sold with smaller spreads and less price impact.

"illiquidity discount", or analogously a "liquidity premium."

Tokenizing relatively illiquid assets and creating a market in which to trade these tokens can reduce the illiquidity discount substantially by reducing frictions to trade.

the liquidity premium is a component of VC returns.

VCs have historically not gone out of their way to facilitate trade for their LPs.

this liquidity does not require a redemption on the part of the fund.

since tokens are highly divisible, it eliminates the need for minimum investments.

Blockchain facilitates trade in the secondary market.

One day you might be able to buy $10 of a single commercial real estate asset like the Empire State Building, or invest $100 in the development of a LEED-certified housing project.

Real estate appraisers will become more like equity analysts, because the market value of any building will be readily apparent if the token is trading.

tokenize your house instead of taking out a traditional mortgage.

small donors will collectively acquire a Picasso for their local museum through a token sale even though none of them possess the resources to acquire the painting individually.

traditional assets currently represent aggregate market value that is orders of magnitude greater than cryptoassets.

the illiquidity discount on global commercial real estate is about 40–50x the aggregate value of all cryptoassets

If a token is thinly traded it is still relatively illiquid.

Traditional asset tokens are less common and perhaps less interesting than protocol tokens.

Traditional asset tokenization is going to impact protocol valuation because they will become intertwined.

annotated article // People’s Policy Project

waves of mergers and acquisitions coupled with virtually non-existent antitrust enforcement have greatly consolidated industry in America

markets that were once home to robust competition from dozens of firms are now dominated by a select few

anti-trust = centerpiece of new Democratic agenda

"common ownership critique” = since public companies are owned by the same set of investors, it hardly matters which one you choose

zero-sum competition is of no use to diversified shareholders

not clear if the theorized problems actually manifest

if this is right, antitrust remedies aimed at increasing the # of firms will be inadequate

Two ways of reconciling this:

Common ownership doesn’t really matter — in practice, these companies really do compete hard, compensation is based on competitive success, etc

leads to market socialist conclusion — not necessary to have competing ownership groups provided we have competing firms

“People who think common ownership through diversified shareholders can work well enough also believe, whether they realize it or not, in the viability of simulated competition in a socialist society.”

real-life examples: Alaska, Norway

Common ownership is a serious problem to be addressed

no clear proposals for how to do that

Objective vs subjective Bayes

subjective Bayes: all probabilities are just opinion

the best we can do with an opinion is make sure it isn’t self contradictory

satisfying the rules of probability is a way of ensuring that.

objective Bayes: there exists a correct probability for every hypothesis given certain information

different people with the same information should make exactly the same probability judgments

In the objectivist stream, the statistical analysis depends on only the model assumed and the data analyzed. No subjective decisions need to be involved. In contrast, "subjectivist" statisticians deny the possibility of fully objective analysis for the general case.

Bayesian inference – how an ideal perfect reasoner would respond to certain pieces of information

“The essence of rationality lies precisely in the existence of some constraints.” — Ariel Caticha

“A Bayesian is one who, vaguely expecting a horse, and catching a glimpse of a donkey, strongly believes he has seen a mule.”

Bayesian methodology

use of random variables to model all sources of uncertainty

requires you to determine a prior probability distribution, taking into account all available information

the posterior distribution becomes the next prior

useful to contrast against frequentist methodology – for a frequentist, the probability of a hypothesis is either 0 or 1

by contrast, for a Bayesian, it can be in a range from 0 to 1

frequentist interpretation supports the statistical needs of experimental scientists and pollsters

probabilities can be found by a repeatable objective process, rather than by opinion

frequentist and Bayesian interpretations are not in conflict – rather, the former provides guidance for how to apply probability theory to the design of practical experiments and the gathering of evidence

A Frequentist is someone that believes probabilities represent long run frequencies with which events occur

History

Thomas Bayes first proved a special case of what’s now called Bayes’ Theorem in the mid 1700s.

It went by the name of “inverse probability”, because it infers backwards from observations to parameters, from effects to causes.

In the 1800s, Pierre-Simon Laplace introduced a general version of the theorem.

Weaknesses of Bayesian analysis

choice of prior — if your priors are bad, then your results will be bad

computationally intensive, especially for models involving many variables

Bayesian approaches often lead to an answer that is a probability statement. Something like, for example, there is a 95% probability that the population mean is between 2.3 and 4.2 (given the data I observed).

A frequentist approach to the same problem leaves an answer that is a statement of "confidence" rather than probability. Something like, for example, with 95% confidence based on the data I observed, the population mean is between 2.3 and 4.2.

I have misplaced my phone somewhere in the home. I can use the phone locator on the base of the instrument to locate the phone and when I press the phone locator the phone starts beeping.

Problem: Which area of my home should I search?

Frequentist reasoning: I can hear the phone beeping. I also have a mental model which helps me identify the area from which the sound is coming. Therefore, upon hearing the beep, I infer the area of my home I must search to locate the phone.

Bayesian reasoning: I can hear the phone beeping. Now, apart from a mental model which helps me identify the area from which the sound is coming from, I also know the locations where I have misplaced the phone in the past. So, I combine my inferences using the beeps and my prior information about the locations I have misplaced the phone in the past to identify an area I must search to locate the phone.

Suppose you have no data ("no beeps"), could you make a probabilistic inference? Yes, you can, says the Bayesian, because you have prior knowledge about where you usually leave your phone (very likely) - but no, you cannot if you are a frequentist, since only data are random. -- It is here (I find) that one sees the "beauty" and consistency of Bayesian reasoning, because probabilistic inference without new data IS natural and the Bayesian nicely integrates how new data (beeps) should influence the inference.

Tossing a coin n times and estimating the probability of a heads (denote by p). Suppose, we observe k heads. Then the probability of getting k heads is: P(k heads in n trials) = (n, k) p^k (1-p)^(n-k).

Frequentist inference would maximize the above to arrive at an estimate of p = k / n.

Bayesian would say: Hey, I know that p ~ Beta(1,1) (which is equivalent to assuming that p is uniform on [0,1]). So, the updated inference would be: p ~ Beta(1+k,1+n-k) and thus the Bayesian estimate of p would be p = 1+k / (2+n).

annotated article // Economist

growing body of research shows positive effects on health/aging/longevity

linking a young rat to an old one can boost the older one’s bone density

mammalian bone density usually drops with age

elderly rats which shared blood with young ones also lived 4-5mo longer

“parabiotic disease”, in which one animal’s immune system rebels against the foreign blood, can be a problem

research had more or less died out by the late 1970s

modern interest began again in 2005

injured muscles of an old mouse heal more effectively when joined with young mice

doubled or tripled proliferation rate of liver cells

works backwards, too

old blood can impair neuron growth in young brains and decrepify youthful muscles

operates across species

infusing old mice with blood from the umbilical cords of infant humans improved their performance on memory tests

less clear what the mechanism is

the working theory is that chemical signals in young blood are doing something to stem cells in older animals

stem cells are special cells kept in reserve as means to repair and regrow damaged tissue. Like every other part of the body, they wear out as an animal ages

something in the youngsters’ blood seems to restore their ability to proliferate and encourages them to repair damage with the same vigor as those belonging to a younger animal would

researchers have been comparing the chemical composition of old and young blood, searching for those chemicals that show the biggest changes in level between the two

oxytocin – transmitter of signals between neurons

proteins GDF-11 and TGF beta-1 – affect cell behavior

B2M – affects the body’s ability to absorb iron from food

cells from the young animal, rather than chemicals in its blood, could be doing some of the work

only a few cells from a younger mouse take root in an older animal

the number of cells may not reflect their importance

some companies are setting up trials

using donated blood plasma

because blood plasma is a natural product, it is not patentable – hard to get drug companies to sponsor certain areas of research, like Ambrosia

there is research into seeing if (a) the treatment is safe and (b) it can reverse some of the effects of Alzheimers

blood transfusions are routine procedures

reversing Alzheimers seems to happen in mice

occasionally get immune reactions even with well-matched donors, sometimes anaphylaxis

if the treatment is safe, he says, and if it proves effective, then the next step will be to identify and isolate the responsible compounds

such compounds would be patentable—particularly if they were then made synthetically

there is simply not enough donated blood around to treat the world’s 44m Alzheimer’s patients with plasma extracts

it’s been difficult to replicate results of certain studies

“talk of reversing aging is premature”

annotated article // Wikipedia

the incidence of cancer does not appear to correlate with the number of cells in an organism.

If the probability of carcinogenesis were constant across cells, one would expect whales to have a higher incidence of cancer than humans.

humans were much less susceptible to cancer than mice

Within members of the same species, cancer risk and body size appear to be positively correlated

strong statistical evidence of a relationship between cancer incidence and height

cancer incidence was lowest in the smaller dog breeds

evolutionary considerations were likely responsible for varying per-cell carcinogenesis rates across species.

The evolution of multicellularity has required the suppression of cancer

In order to build larger and longer-lived bodies, organisms required greater cancer suppression.

the advantage of preventing cancer these genes conferred was, for moderately-sized organisms, outweighed by their disadvantages—particularly reduced fertility

promising discoveries

genes in the bowhead whale (Balaena mysticetus) that may be associated with longevity.

polysaccharide in the naked mole-rat that appeared to block the development of tumors.

elephants have 20 copies of tumor suppressor gene TP53 in their genome, where humans and other mammals have only one.

hypotheses

"larger organisms have bigger and slowly dividing cells with lower energy turnover, all significantly reducing the risk of cancer initiation."

cell size

cell size is not uniform across mammalian species, making body size an imperfect proxy for the number of cells in an organism.

the volume of an individual red blood cell of an elephant is roughly four times that of one from a common shrew

larger cells divide more slowly

compounds exponentially

mathematical models of cancer incidence are highly sensitive to cell-division rates.

lower basal metabolic rates

less damage over time per unit of body mass.

In larger organisms, tumors need more time to reach lethal size, so hypertumors have more time to evolve.

cancer may be more common and less lethal in large organisms

experiments

article // annotated

complexity of exports is a strong predictor of a country’s future economic growth

complexity = diversity of exports + the expertise and technological infrastructure required to produce them

the more complex a country’s products, the more equality it enjoys relative to similar-sized countries with similar-sized economies.

inequality lives within a range of values that are determined by your underlying industrial structure.

when all the money is coming in from one industry, and the 30,000 people involved in that industry of course are going to have an advantage in the economy.

by contrast, when many people are generating money in many different industries, small groups have less of an overwhelming advantage

why does complexity work as a measure?

it factors in the infrastructure and institutions that facilitate the aggregation of knowledge

e.g. reliable transportation and communication systems, a culture of trust that enables productive collaboration

methodology – compared each country’s complexity measure to its Gini coefficient

results

per-capita GDP predicts only 36% of the variation in Gini coefficients

product complexity predicts 58%

Combining per-capita GDP, export complexity, education levels, and population predicts 69%

complexity measure captures something crucial that the other factors leave out.

examples

countries whose economic complexity increased, such as South Korea, saw reductions in income inequality

article // annotated article

we take for granted inner-city ghettos, but they were not a natural occurrence

these neighborhoods are a direct result of government intervention, specifically in real estate policies

New Deal programs like the PWA (Public Works Administration) and the FHA (Federal Housing Administration) created segregated housing where there hadn’t been before

not just in the South

Detroit, Atlanta, St Louis, the SF Bay Area

this wasn't personal choice, or even the influence of real-estate professionals, but government policy

the FHA guaranteed bank loans for subdivisions for white workers

the loans were conditioned on the builder promising to not sell homes to African Americans

they even required builders to attach restrictive covenants to deeds so owners couldn’t sell to AAs

this was done in the name of “protecting homes as an investment”

white families were lured to the suburbs by cheap, guaranteed mortgages

industry moved to the suburbs too, to follow these workers

AAs were stuck in the cities, locked out of these new artificial opportunities, because laws literally prevented them form moving to the suburbs

there were fewer jobs for AAs left in the cities

George Romney once said housing policies had created a “white noose” around black ghettos that should be “untied”

every educated person knew about this 50 years ago, but America as a society has forgotten this history

not even mentioned in major US history books

American wealth today is primarily in housing

Street networks in Osaka, Kyoto, and Tokyo are highly connected. The streets are narrow, and the blocks are short, which feels more human-scale and creates more opportunity for diversity . Pedestrians feel comfortable in these dense networks, which encourages walking and biking.

This Kyoto side street would barely be enough space between buildings to conform to most American zoning codes, let alone to count as a street.

Short blocks break the social isolation of wide, long streets. Pedestrians are more likely to stop by a shop as they walk past than if they were driving, and by permitting alternative travel routes and shortening the travel distance from nearby places, short blocks open greater access to stores and services.

This mid-sized street in Japan would be a small alley in an American city. Cars go both directions, so they are careful. This makes pedestrians and cyclists comfortable to walk in the middle of the street (like you can seen in the picture above!). White lines delineate the center from the sides, which helps separate traffic and pedestrians when need be, but people are as if not more welcome than cars here.

It's useful to contrast these human-scale streets with their American counterparts. San Francisco's South of Market (SoMa) neighborhood is an interesting case. The district's legacy as an industrial zone left it with wide streets and longer blocks, and the effect is that pedestrians feel like second-class citizens. Cyclists are The 280 and 101 freeways furher emphasize this isolation by slicing right through the neighborhood.

It's no coincidence that the SF neighborhoods people most often describe as "charming" are the ones whose with smaller streets and shorter blocks. These tend to be the older ones north of Market St like Hayes Valley, Lower Pacific Heights, and the Castro.

The continuity of urbanism along the 500km shinkansen bullet train track between Osaka and Tokyo was astonishing. Throughout the journey, the buildings almost never thinned out, and at no point did I feel like we were in suburbia, let alone true countryside. The route went through Kyoto and Nagoya, both major cities in their own right, and there was a continuous metropolitan zone along the entire shinkansen line.

At the same time, I was surprised by Japan's lack of density, especially in Tokyo. I didn't find any one area that felt especially built up. The entire metropolitan area is highly populated, and the median building height is greater than most American cities, but there was no central urban core with significantly higher density than the surrounding areas. Instead, the height level of buildings was mostly continous across all neighborhoods. By contrast, major American cities tend to have an extremely dense, bustling center with steadily decreasing density in neighborhoods radiating out from that core. This is usually a business and shopping district with high rise apartments. Many people live in that center, but even more commute in and out each day for work.

Japanese cities' lack of centers with extreme density surprised me. My intution about how cities formed was a life-scale Hotelling Game , in which the optimal location for a new enterprise is in the middle of where everything else is. This minimizes the distance to the greatest number of amentities, shops, people, and so on, and so it is the highest value land. Businesses want to be where people are, and people want to live close to their schools and work. This creates a cycle in which city centers are valuable, incentivizing developers to build denser, taller buildings. As more people in, the land in those centers because even more valuable, which incentivizes more building. With all these uses vying for the same space, the only alternative to build up, and you get urban cores with a far greater average building height than the surrounding areas. (Of course this is a simplification — zoning rules, geography, weather, and more affect land values, too. But the Hotelling dynamic plays a role in shaping the density and land values of cites. You can see the effect in the Google Earth images of New York and San Francisco below.)

Google Earth view of Manhattan _. The Financial District on the south end of the island and Midtown just below Central Park are extremely dense. Concentration of people draws in businesses and shops, which in turn makes it a more attractive place to build housing, transit, and amenities. Meanwhile, building height drops off quickly outside of these centers. The median number of floors in Greenwich Village (around Washington Square Park) is less than four!_

Google Earth view of San Francisco _. San Francisco is a striking illustration of this phenomenon. It's is a bit unfair, because most in neighborhoods outside of the Financial District and (_ as of 2015 ) Mission Bay, buildings are limited to 4-6 stories. However, the SF's neighborhoods for the most part took on their current form before building codes cemented it, so Hotelling still provides a useful model.

Japanese cities don't appear to follow this logic. Tokyo's tall buildings are fairly even distributed throughout the city. There is variation of course, and neighborhoods like Ueno are more spread out than others, but there is no single area that is far taller than the rest. The closest thing to "downtown" was the area around Tokyo Station, but that was more a function of its role as an intercity transit hub connecting the shinkansen lines than of being the central business district.

Google Earth view of central Tokyo .

I'm still at a loss as to what caused this dynamic. My best guess is that the city developed alongside a mature, well-supported rail system that could whisk people from one part of the city to another, so the advantage of being in the middle of it all was lower. Manhattan's subway system could be described in much the same way though, so this answer is not satisfying.

Japanese land use regulations are also very different from their counterparts in the US , so that certainly played a part too. It's possible that this accounts for most of the difference. In the San Francisco most neighborhoods limit buildings to 4-6 stories, which artificially enforces the funnel shape, where the old parts of the city that were dense before regulations took hold are the only place where tall buildings are allowed in the first place. Other US cities follow a similar regulatory pattern. This raises an interesting question — if SF lifted all density limits, where would we see growth? Would the financial district grow even taller, or would the surrounding neighborhoods build out to match its height? My guess is it would be a mixture of the two, with further densification of the core as well as development of the surrounding areas, with lessening growth as you went outward. Overall though, the effect would likely be an evening of heights across the city. I'd guess that the variance in median heights between neighborhoods would decrease, and we'd have a situation closer to that of Tokyo.

I'm not well-versed in the history of Japanese land use. So if you have any other ideas about why their building height variance is low, please let me know!

Urban kchoze: Japanese zoning (annotated) // Urban kchoze: euclidian zoning (annotated)

Summary

The Japanese system is inclusionary, as contrasted to the exclusionary system common here in the US. The typical zoning form in America is called euclidian zoning, which specifies the allowed uses and dimensions for a zone. Japan zones limit the "maximum nuisance” in a zone, and allow for any development below that threshold (e.g. a factory can’t be built in a residential neighborhood but housing can be built in a light industrial zone). You can think of this as whitelist vs blacklist approaches. The result in the Japanese case is a lot more mixed use development, while in the US land use is a lot more segregated.

American zoning practices: Euclidian zoning

a typical American suburb comprises blocks of nearly identical single-family homes

this is not an emergent phenomenon, where individuals just happened to all choose to build their homes in the same way

zoning defines and strictly limits urban developments

in N America, the typical standards are what is called “euclidian zoning” (from the city of Euclid, Ohio)

extremely strict

considers single- and multi-family homes to be two separate uses to separate, as are semi-detached houses and fully detached houses (contrasted against European and Asian zoning, which consider residential as residential)

originates from racial segregation

at first, zoning explicitly banned certain races

when it was ruled unconstitutional, they used different ways to achieve the same result

minorities were disproportionately poor — more likely to rent, and when they were owners they tended to buy smaller homes => so zoning (a) banned multifamily buildings in single-family areas and (b) established minimum lot and building sizes

greatly limits density

why?

simple to enforce – simply measure dimensions and see if they conform to the rules

satisfies those with a desire to control the built area of their immediate neighborhood, but terrible for macro-management of decent communities

the neighborhood doesn't change much once it's built up => NIMBYs love it

consequences

delays/kills projects => strangles redevelopment and “keeps neighborhoods in formaldehyde”, effectively makes change illegal

ultimate empowerment tool for NIMBYs

ironically, it means that the only time it's worth it for developers to confront NIMBYs is to build condo towers, because the profit of denser units justifies fighting for it

yet duplexes/rowhouses/etc would be a better, more gradual evolution

results in sprawl; easier to build out than densify

if the land is reserved only for single-family detached houses, then the profit value of each square foot is kept artificially low

oversupply of single-family lots

shortage of land for multifamily and commercial development

encourages corruption

when zoning blocks a highly profitable project, you need a zoning modification to let it through

developers have an incentive to buy off elected officials

Japanese zoning practices

zoning is a national law, not a municipal by-law

in the US, cities control their own zoning; but many cities (especially smaller ones) don't have the expertise to plan a city decently

in Japan, the national government mobilizes expertise to make a good set of laws

local application is left to city governments, so cities have the execution power, but they have guidelines to work off of

downside – fewer possibilities for experimentation

there are only 12 zones

range from low-rise residential zones to exclusively industrial zones

in the US, there are often hundreds of different zones

zones allow a “maximum use” rather than an exclusive use for each zone

the Japanese principle is to include all uses up to a maximum “nuisance level”

every use considered less of a nuisance than the set zone is allowed, so low-nuisance uses are allowed everywhere

as a result, almost all Japanese zones allow mixed use developments

in N American zoning, a zone clearly specifies what is allowed in it (a sort of “whitelist” approach), and zones allow only one or two uses

planning departments must micromanage the smallest detail – if they forget to zone for enough commercial zones or schools, they need to change the zoning later and therefore confront NIMBYs

a lot of needed uses are forgotten => they then have to be built on the outskirts of the city

hyper-competent micromanaging is much reduced in Japanese planning

doesn't differentiate different types of residential use

N American zoning tends to treat single-family and multifamily as two separate uses to keep segregated

in Japan, if a building is used to provide a place to live to people, it's residential, that's all – whether it's rented, owned, houses one or many households, it doesn't matter

maximum ratios of building to land areas still restrict how high and how dense residential buildings may be, so you're not going to get a 10-story apartment block in the middle of single-family houses

in American cities, if the planning department doesn't plan for enough multifamily or single-family zones, you can create big problems

there may be shortages of either multifamily or single-family zones, pushing prices up for that kind of housing

in practice, it's most often rental units that get the shaft, resulting in sky-high rents as there is a rental unit crisis (ahem, San Francisco...)

in Japan, multifamily homes tend to congregate around schools, commercial sectors or train stations. This makes sense, because the $$ per square foot of land of multifamily uses is higher than for single-family homes

rational rather than arbitrary height limits

the farther a building is set back from the street and the wider the street, the higher it can be

rules sometimes omitted when they want to build higher buildings

in the US, rules are often determined by what's already in the neighborhood

cities have the right to make exceptions, require certain geometric criteria, etc

but the defaults are set by the national government

results

the Japanese model has created/protected urban settings that are far more people focused and walkable

much more market-based, responsive to demand

this isn't the only model

blog post // annotated

formal logic gives us two properties to describe any evaluation procedure:

soundness – a sound jury will never send a guilty person free

completeness – a complete jury will never send an innocent person to jail

soundness and completeness are orthogonal: you can have any combination of soundness and completeness

a sound type system (or analysis) is one that rejects all erroneous programs, and a complete system accepts all correct programs

which is more important for static analysis?

sound analyses compose

many of the properties you really want to have verified (such as “does this rendering look right?”) don’t fall in the scope of the verification system

which is more important for type systems?

a sound type system is one that is not lenient – it rejects all invalid programs plus some number of valid programs

a complete type system accepts all valid programs, and some invalid ones to boot

the answer isn't quite as obvious as in static analysis

a programming language with a complete and unsound (static) type system has a fallback in the form of dynamic typing

Dependent type systems therefore blur the distinction between compile-time type checking and runtime type checking, and thus between static and dynamic typing.

Programmers dislike having the computer reject a program that would have run fine, simply because the computer couldn’t make sure it would run fine without actually running it

The target domain matters

Wikipedia article // annotated

Flynn effect – the substantial, long-sustained increase in intelligence test scores measured in many parts of the world from roughly 1930 to the present day

IQ tests are standardized with the average result set to 100. But when the new test subjects take older IQ tests, in almost every case their average scores are significantly above 100.

Test score increases have been continuous and approximately linear.

Similar improvements have been reported for other cognitions such as semantic and episodic memory.

The increasing test performance over time appears on every major test, in every age range, at every ability level, and in every modern industrialized country.

May have ended in at least a few developed nations.

Proposed explanations include: improved nutrition, a trend toward smaller families, better education, greater environmental complexity, heterosis (decreased inbreeding), the gradual spread of test-taking skills

Too rapid for genetic selection to be the cause

Schooling and test familiarity

Many studies find that children who do not attend school score lower on the tests than their regularly attending peers.

Children who take the very same IQ test a second time usually gain five or six points.

Some preschool (ages 3–4) intervention programs like "Head Start" do not produce lasting changes of IQ, although they may confer other benefits.

High correlation between rising literacy rates and gains in IQ

Generally more stimulating environment

Increase of exposure to many types of visual media.

Gene environment correlation – those with a greater IQ tend to seek stimulating environments, which may further increase IQ.

This effect also decays over time unless the stimulus continues

Nutrition

Increase of average height of ~1 cm per decade.

analogous increases of head size, and by an increase in the average size of the brain.

However, groups who tend to be of smaller overall body size (e.g. women, or people of Asian ancestry) do not have lower average IQs.

Nutrition hypothesis predicts that gains will occur predominantly at the low end of the IQ distribution

An alternative interpretation of skewed IQ gains could be that improved education has been particularly important for this group.

Decrease in infectious diseases

US states with higher prevalence of infectious diseases have lower average IQ, even after controlling for wealth and education

Possible end of progression

the increase of scores of general intelligence stopped after the mid-1990s

Difficult to interpret since these countries have had significant recent immigration from countries with lower average national IQs.

There is a limit to how much environmental factors can improve intelligence.

During the last century, there is a negative correlation between fertility and intelligence

Applying Cognitive Psychology to Enhance Educational Practice // annotated

Retrieval as a Memory Modifier

Retrieval itself can affect our memories

Tests provide opportunities for learning

When information is successfully retrieved from memory, its representation in memory is changed such that it becomes more recallable in the future.

Multiple choice vs cued recall

Multiple choice directs attention more broadly – not just to info pertaining to the question, but also to info pertaining to the alternatives.

When solving multiple choice, students retrieve information about why the other answers are incorrect in order to reject them. This requires recall of information pertaining to those alternatives, which serves as a learning event for both the tested and untested information.

Retrieval-induced forgetting = impaired access to non-retrieved items that share a cue with the retrieved ones

For example: If you ask someone to name an item associated to a cue and beginning with a certain set of letters (e.g. a fruit starting with “or____”, which gives you “orange”), it reduces later access to items that share that queue (e.g. “banana”).

Inhibitory processes that help facilitate the retrieval of the target by reducing access to competitors.

Retrieval-induced forgetting is an adaptive aspect of a functional memory system.

Retrieval success is not a necessary condition for retrieval induced forgetting.

Items that suffer from retrieval-induced forgetting benefit more from relearning than control items

New theory of disuse

Two indices of memory strength:

Storage strength (SS) – how well learned something is

Retrieval strength (RS) – how accessible (or retrievable) something is

RS will decrease over time, especially for information with low SS.

The more SS information has, the bigger the boost in RS it will receive as a consequence of restudy

e.g. You can relearn a childhood address much more quickly than a new address, even if you can’t recall either of them initially

The more RS that information has, the smaller the boost in SS as a consequence of restudy

e.g. Simply repeating to-be-learned information over and over again is not very helpful for really learning that information

How We Learn Versus How We Think We Learn: Desirable Difficulties in Theory and Practice

Performance during training is not always representative of long-term learning.

Desirable difficulties

Interleaving many different types of problems during training produces higher scores than repeatedly practicing a single type of math problem.

Certain training conditions that are difficult and appear to impede performance during training yield greater long-term benefits.

Strategies:

Spacing, rather than massing repetitions

Testing, rather than re-studying information

Varying conditions of practice, rather than keeping them constant

Accessibility Principle – Reduced accessibility increases learning of that information

Reducing the accessibility of information in memory fosters additional learning of that information when it is successfully retrieved.

Spacing

It is common sense that when we want to learn information, we study that information multiple times. The schedules by which we space repetitions can make a huge difference, however, in how well we learn and retain information we study.

Distractor tasks

Increasing the difficulty of a distractor task (without changing the duration of the spacing interval) leads to improved learning, much like a spacing effect.

The accessibility principle may be a kind of law of memory, even if the effect of spacing per se is not.

Increasing accessibility reverses the spacing effect.

An optimal learning schedule is one with expanding retrieval practice, rather than equally spaced practices.

This is one of the most robust results in all of cognitive psychology.

When spacing intervals are too long and repetitions do not retrieve previous presentations, then the study-phase retrieval theory predicts no benefit of spacing.

Generation

Generating words makes them more memorable (rather than simply reading them).

e.g. letter-stem queue (“fl_____” for “flower”), unscrambling an anagram (“rolwfe” for “flower)

Interleaving

Spacing calls for intervals of time in between repetitions, and this may not be the most efficient use of time. To get most of the benefits, you can interleave activities.

Imagine you have three final exams to study for. If you were to space out study of three whole courses, you might as well start your course review before the quarter even begins! Particularly when one has several different things to learn, an effective strategy is to interleave one’s study: Study a little bit of history, then a little bit of psychology followed by a chapter of statistics and go back again to history. Repeat (best if in a blocked-randomized order).

Interleaving requires learners to constantly “reload” motor programs (in the case of motor skills) or retrieve strategies/information (in the case of cognitive skills).

Reloading/retrieving info repeatedly (rather than having them “cached”) allows learners to extract more general rules that aid transfer.

Spacing alone and interleaving alone offer benefits to inductive learning performance. However, combining the two does not provide additive benefit.

Perceptual disfluency can be a desirable difficulty.

Examples of perceptual disfluencies: fonts that are difficult to read, words in very small print

The difficulty of processing disfluent information can actually lead people to engage in deeper processing strategies, which then results in higher recall for those items.

Perceptual disfluencies can hurt people's *estimations *of how well they will remember info, even while it in fact helps their memory.

Interactions between desirable difficulties

Further study needed on how combinations of desirable difficulties interact.

While spacing and variation are each independently “desirable”, there is a sub-additive interaction between the two.

At longer spacing intervals, variation actually hurts memory performance.

Many students believe that studying examples of a category all at once leads to more effective inductive learning. However, the opposite is in fact true – studying them intermixed with examples of other to-be-learned categories is far more effective.

Goal-Directed Forgetting

People often view forgetting as an error in an otherwise functional memory system

Yet forgetting is adaptive in many circumstances.

e.g. If you park your car in the same lot at work each day, you must inhibit the memory of where you parked yesterday to find your car today.

Mechanisms of inhibition – analogous to those in vision – play an important role in goal-directed forgetting

Interesting test results

If a list is tested after the learner was notified that it would not be tested, the learner will show weaker recall for that list.

A similar pattern is observed in an item-based method, in which participants are told after each word whether or not it will be tested.

Recall of any list that was expected to be tested will be greater than that of the baseline condition.

Further questions for study

Does the pattern of results extend beyond simple word lists to more educationally relevant materials, such as text passages or videos?

What happens to the pattern of results when information between the two lists is related?

Metacognition

Metacognition – subjective awareness of one’s own knowledge

Learners often fail to take into account that forgetting occurs over time and that learning occurs with repetition. They instead seem to assume that what they know at the time the judgment is made is an accurate reflection of what they will know at a later time point.

Awareness of study strategies

People tend to think massed repetitions are more effective than spaced repetitions.

Massed repetitions lead to greater short-term performance, but impair long-term performance.

Greenhouse Effect from the Library of Economics and Liberty // annotated article

What Is It? How Serious Is It?

Because no one owns the atmosphere, no one has a sufficient incentive to take account of the change to the atmosphere caused by his or her emission of carbon.

Climates will change more in the next one hundred years than in the last ten thousand.

Meteorologists predict greater temperature change in the polar regions than near the equator.

Carbon dioxide has increased about 25 percent since the onset of the industrial revolution.

The increase in carbon dioxide will, by itself, cause the greenhouse effect, but other changes in the universe may offset it.

Likely minimal effects in developed countries

If you to ask a 75-year-old farm couple, “Would the change in the climate be among the most dramatic changes in either their farming or their lifestyle?”, the answer would most likely be no.

Little of our gross domestic product is produced outdoors, and therefore, little is susceptible to climate.

Agriculture and forestry are less than 3 percent of total output

It is not at all certain that the net impact of climate change on agriculture will be negative

Agricultural productivity in most parts of the world continues to improve

Many crops may in fact benefit directly from enhanced photosynthesis due to increased carbon dioxide

Its Effects on Developing Countries

Greater effect on developing countries than developed ones

Agriculture provides the livelihoods of 30% or more of the population in much of the developing world.

Parasitic and other vectorborne diseases affecting hundreds of millions of people are sensitive to climate.

The trend in developing countries is to be less dependent on agriculture.

Vulnerability to climate change should diminish.

Their best defense against climate change will be their own continued development.

Why Should Developed Countries Do Anything?

Doing something worthwhile would cost about 2% of GNP in perpetuity.

The developing countries would probably clamor, understandably, to receive the resources immediately in support of their continued development.

It is difficult to know how to value what is at risk, and difficult even to know just what is at risk.

Atmospheric or oceanic circulatory systems may flip to alternative equilibria, producing regional changes that are sudden and extreme.

If the gulf stream flipped into a new pattern, the climatic consequences might be sudden and severe.

A better question—assuming we were prepared to spend 2 percent of GNP to reduce the damage from climate change—is whether we might find better uses for the money.

What Solutions Are Proposed?

Some ideas

Reducing energy use and the carbon content of energy have received most of the attention.

A new forest will absorb carbon until it reaches maturity

Stopping or slowing deforestation is important for other reasons but is quantitatively more important than reforestation, partly because forest subsoils typically contain carbon greater than the amount in the trees themselves

substances or objects can be put in orbit or in the stratosphere to reflect incoming sunlight.

stimulating cloud formation

huge mylar balloons in low earth orbit

universal carbon tax

tradable permits (cap and trade)

It is improbable that the developing world, at least for the next several decades, will incur any significant sacrifice in the interest of reduced carbon

it would increase the costs to the developed world by at least another percent or two

Universal carbon tax

A carbon tax would require no negotiation except over a tax rate and a formula for distributing the proceeds

Would currently yield close to half a trillion dollars per year in revenue, almost 10 percent of our GNP

Politically infeasible on a global scale

Tradable permits (cap and trade)

Would have to be renegotiated every few years as to what the “equitable distribution” is

selling an emissions right will be perceived as evidence that a quota was initially too generous

Marshall Plan aid after World War II is a useful model for thinking about how to handle the coordination problem

all the submission of data and open argument led, if not to consensus, to a reasonable appreciation of each nation's needs.

The Dream of Owning a Home: The History of the American Mortgage // annotated article

the mortgage has precedent in ancient marine insurance

maritime law allowed for “bottomry bonds”, loans made on merchants' ships that were repaid with interest once the ships arrived safely at their destinations

the most logical method of advancing a loan for the acquisition of a ship was by mortgaging the ship itself

between 1949 and 2000, mortgage debt relative to total average household income rose from 20% to 73%, and from 15% to 41% relative to total household assets

until 1913, national banks were technically restricted from directly investing in mortgages

loopholes were extensively used

postbellum period up to 1900

late 1890s: the average life of a mortgage was <6 years and accounted for <40% of the real property value

the mortgage market in the postbellum period was a disintegrated network of unevenly allocated mortgage funds

market segmentation favored the Northeast with lower interest rates, while hitting the areas of greatest growth in the West with the highest interest rates

the majority of lending institutions were in the NE

despite high interest rates, Western cities doubled in population between 1880 and 1890

the asymmetry in lending practices likely constrained growth in new cities while still allowing established cities grow rapidly

in early 1900s, mortgages featured:

variable interest rates

high down payments

short maturities

during Great Depression, federal govt intervention changed mortgage market

at lowest point of GD, 1/10 of all homes were in foreclosure

federal govt created:

Home Owner's Loan Corporation (HOLC, 1933)

Federal Housing Administration (FHA, 1936)

Federal National Mortgage Association (Fannie Mae, 1938)

these institutions were designed to provide govt-sponsored bonds to reinstate mortgages in default by extending terms and fixing rates to create self-amortizing loans for the borrower

boosted investor confidence / stabilized market by providing mortgage insurance

G.I. bill for WWII vets formed the Veterans Administration (VA) mortgage insurance program

stimulated the housing market

extended the maximum mortgage term to 30 years

1968: established Government National Mortgage Association (Ginnie Mae) to “keep the mortgage market liquid” by bringing uniformity, inventing standards / new financial instruments

1970: Federal Home Loan Mortgage Corporation (Freddie Mac) formed to provide liquidity in the secondary mortgage marketplace => purpose was to further promote home ownership

Debtor Nation: The History of America in Red Ink // annotated review

first personal loan department (PLD) in USA opened in 1928 in NYC

initially saw it as more public outreach than a source of profits

commercial banks had always made small loans on the side for good customers who borrowed large sums of $$ for business, but these “accommodation” loans never made $$

few other banks opened these departments in late 1920s

standard part of commercial banks' offerings by end of 1930s

why would bankers not lend $$ to consumers?

in 1920s, banks earned easy profits from lending to business in expanding economy => no need to explore new opportunities

institutions weren't equipped to handle consumer lending

when bankers pictured a PLD, they envisioned the methods used for commercial loans jsut for much smaller amounts

more paperwork and expenses for staff/investigation/advertising/collection than commercial loans

early experiments in personal lending were guided by the moral outlook of bankers

unexpectedness of need – in contrast to installment credit – morally justified personal loans

before they were allowed to borrow, debtors had to learn to deposit => after repayment, borrowers would still have a savings account, which bankers hoped they would continue to use to avoid future need of loans

FHA's Title I modernization loan program transformed personal lending (1934)

meant to stimulate as much demand as possible during Great Depression

guaranteed profits for bankers, through FHA insurance program

investment opportunities were relatively hard to find during GD, because businesses avoided borrowing to expand their operations

between 1929 and 1932, consumer spending fell by 1/5, and nonresidential business investment fell by >2/3

personal lending helped many banks survive the Depression

shift from accommodation loans from long-time banker to impersonal system of evaluation/profit

loosening social bonds

commercial banks no longer only for wealthy businessmen, but also new middle class

medical expenses and loan consolidation drove the personal loan business

health insurance was relatively rare

smoothed out disruptions in income

key difference between loans at the bank vs installment plan or loan shark was that the enforcement of a bank loan never meant losing a valued possession or limb

personal loans could protect the equity of installment purchases

lending to salaried employees was extremely safe

class filter of feeling comfortable walking into a commercial bank

underpinned by salaries and character – not assets or collateral

business loans traditionally determined on value of liquidation of the firm's assets, not ability to repay

the “habit of the borrower” could be easily found through the local credit bureau

existing infrastructure for the FHA programs made easy the transition into personal loans

personal loans were simply Title I loans for everything else and w/o the govt guarantee

success centered on volume

rather than a few airtight loans, a group of personal loans had to be certain only on average

adopted Fordism/assembly line

small loan companies catered to working class; commercial banks lent to middle class

repeat business formed large fraction of business

consumer lending continued to expand w/o federal assistance

Debtor Nation: The History of America in Red Ink // annotated review

the 1930s marked a moment of doubt about the future of capitalism, making govt intervention experiments politically viable

some within the administration saw this as an opportunity to sidestep the constraints of the market economy

others saw it as a chance to create new directions for private investment

practical solutions in a desperate time, more than ideology, guided Roosevelt's policies

FHA changed the way banks operated forever by turning mortgages into nationally-traded commodities

flood of funds, guaranteed profits, standardized policies

the Public Works Administration (PWA) created & underfunded work relief programs

attracted criticism from all sides for doing either too little or too much

PWA decided what to do / how to do it, but passed most costs to local government

lacked funding => PWA's vision for restoring the economy by restoring the cities came to little

the real innovation of New Deal policy was the practical harnessing of private capital for social ends

using markets rather than govt spending to provide housing/stimulate the economy was controversial

the range of possible interventions in the economy was circumscribed by compliance of the business community

before the 1920s, mortgages were seen as a short-term debt with a certain claim on property, like any other form of consumer lending

after the stock market crash, investors/banks withdrew capital from the mortgage market, making it expensive for borrowers to renew their mortgages

foreclosures during the Depression resulted as much from the drop in home owner's income as from the withdrawal of short-term mortgage funds from the market

without mortgages, the housing industry collapsed

restoring the economy turned on restoring the construction industry

beginning in 1933, creation of Home Owner's Loan Corporation (HOLC) provided much-needed liquidity in the short term

refinanced mortgages on longer terms, up to 15 years

the hope was that by lowering the monthly payments, owners could meet their obligations

20% of loans ended in foreclosure, but the primary aim (restoring liquidity to markets) was successful

restricted to refinancing mortgages in default => stopped hemorrhaging of housing stock, but had no mechanism to revive new construction

idea behind FHA: “a new kind of mortgage instrument which will be the soundest thing in the market, the most approved standards, which will be amortizing and paying off”

homes would be owner-occupied / not speculative instruments

“It was the last hope of private enterprise. The alternative was socialization of the housing industry.”

FHA guidelines deemed what kinds of properties a loan could be procured for

goal = to avoid the shoddy, speculative construction that had been the norm in the 1920s

quality was assured by FHA inspectors + mortgages standardized => investors all over the country could know exactly what a particular mortgage was worth

mortgages could the be resold nationally like any other standardized commodity

enabled the $$ of capital-rich east to flow south and west

FHA insurance program

the federal govt organized the FHA, but private capital paid for and profited from it

compliance with FHA guidelines was mandatory for the insurance

if borrowers defaulted, the insurance program would repay the principal to the lenders

risk was nonexistent

the program was paid for by a 0.5% slice of the interest from every FHA loan

if there were no defaults, lenders got all of the insurance payments back

criticisms of FHA

by focusing on those who were already doing well, the FHA drew fire from critics who believed the govt should be helping the millions out of work / struggling

the idea of expanding American debt seemed suspect at best

criticized for burdening the solvent with debts – did the New Dealers want to bring down the stable portion of society still left?

New Dealers responded that “any measure that increased employment would add wealth and repay that debt”

While PWA was justified by doing work that the private sector could/would not do, the FHA created the opportunity fro the private sector to act

argument for FHA

while the opportunity for profit existed, govt intervention was necessary to reduce the risk of investment

the insurance “furnished a margin of security more important in its psychological effect on investors than the govt's actual financial commitment”

amortized payment plans were far more predictable, less risky

by amortizing payments, need to refinance the principal at the end of 20 years would be gone

extending the mortgage over many business cycles would stabilize the supply of mortgage money

amortization greatly increased the # of Americans who could afford to buy homes

despite the moniker “federally insured”, govt didn't insure the loans – merely set up a system that would function by itself

business enthusiastically endorsed the FHA

no fear of being “crowded out” by the FHA

by working through private channels, didn't seem like another one of Roosevelt's unnecessary, possibly socialist/fascist boondoggles

organized by experienced businessmen

cultivating the consent of business was the foundation of the FHA's success

two types of loans under FHA:

Title I – home improvement / “modernization” loans

Title II – home purchase mortgages

Title I program saw a 40% rise every week between its creation in mid-August 1934 and October

stimulated construction

FHA encouraged suburbanization

housing quality was the foundation of the FHA system

implicit and explicit hierarchies of what home buyer's ought to want

planners' social assumptions/preferences shaped the planning criteria as much as macroeconomic considerations

imagined ideal home as opposite of crowded urban slums

believed that homogeneity of surrounding housing stock indicated stable housing prices

believed multiuse districts threatened residential value

“adverse influences” category of the mortgage application was mostly concerned with the danger of class/racial mixing

believed the city was not a good investment, making suburban lending risk free and urban lending bad business

with the city such a bad investment, the suburb was not a choice, it was *the *choice

protection took a variety of forms – from the man-made “high-speed traffic artery” to natural “hills and ravines” to the social “college campus”

enforcement by “established barriers” or the law was essential to a good mortgage rating

the “lack of appropriate and adequate deed restrictions” to keep out Jews/Asians/African Americans jeopardized the collateral for the mortgage

stimulating demand was a priority

buying used homes created no demand for labor or materials, so FHA guidelines steered buyers towards new homes

space for ample and replaceable furniture was important, since it allowed for greater consumption

While FHA planners were rhetorically ambivalent toward transportation type, they preferred the kinds of places automobiles could get to

housing policies created demand for autos – and automobile financing

without increasing – or at least stable – values, the entire scheme of the long term mortgage would become untenable

PWA policy focused on the rejuvenation of the city; the point of the FHA was to escape the cities, not save them.

possibility of divorcing jobs/housing/investment from a specific location is what gave FHA policies their power

but also constrained their ability to redress economic inequality

in helping to recover the economy through suburbanization, the FHA further entrenched wealth inequality along racial lines

many people left the crowded cities through the FHA, but others – denied access to federal mortgages – were left behind

prior to the FHA, mortgages were extremely local ... unable to lend $$ from a distance, capital tended to accumulate in slow-growth areas and be scarce in fast-growing ones

because all FHA-insured mortgages conformed to standard specifications, the FHA created conditions favorable to a nation-wide mortgage market

w/o local financial borders to stop capital flow, but with federal impositions of max interest rates, mortgage rates converged

individual investors went from 60% of mortgage market in 1900 to ~10% in 1962

competing views between PWA & FHA:

PWA – govt could boost the economy while helping the disadvantaged and boosting the city

FHA – believed the best way to sustainably jumpstart the economy was through loosening private capital

govt language reframed mortgages not as heavy debt, but as responsible long-term investments for the borrower

only when houses began to be seen primarily as investments, rather than debts, could they acquire long-term financing

what had been a marker of financial uncertainty became a marker of financial responsibility