Perceptions and misperceptions in Risk Management
The right answer to the wrong question isnât worth much. Fixed perceptions can bar the path to asking the right questions.
Risk management has as its goal improving decision making in situations of uncertainty. We see the success (or failure) of risk management in achieving this goal as fundamentally dependent on the collection and manipulation of data. We are less likely to explicitly identify the interpretation of data, the choice of data, or the choice of data manipulation methods as also affecting the success of risk management.
However, data selection, manipulation and interpretation are framed by a risk managerâs domain expertise (familiarity with the environment under scrutiny and a known set of quantitative tools proven to be useful in the past).
Domain expertise is, at bottom, a set of ideas about how the world works, how the world can be understood, and how future outcomes (or their relative probabilities) can be manipulated. These ideas, or preconceptions, powerfully affect the solutions risk management will gravitate toward.
Below I discuss specific ways that preconceptions may lead to misperceptions of risk, and suggest mitigants that may limit the potentially adverse consequences of misperceptions in risk management decision-making.
To begin, here is an illustration of the power of preconceptions to influence decision-making.
On the Power of Established Perceptions
At the end of the 19th century, one of the great challenges in naval warfare was the inaccuracy of large guns fired from one vessel toward another. The motion of the rolling sea, making both targeting difficult and firing slow, caused this problem.
Admiral Percy Scott of the British navy innovated a solution by modifying the operation of naval guns in two ways. The first was to change the gear ratio on the elevation mechanism to make it easy for the operator to manipulate the elevation quickly. The second was to change the telescopic sight on the gun so that it would not recoil with the gun when the gun was fired. These modifications enabled the gunner to keep sighting the target continuously, and enabled what he called âcontinuous-aim firing.â
The effect was dramatic. Prior to this innovation an 1899 Naval exercise in which five ships each fired for five minutes at a floating target at the then conventional range of 1600 yards (just under 15oo meters) scored two hits in their twenty-five combined minutes of firing. Six years later a single, Scott-modified gun firing at a similar target recorded fifteen hits in one minute, half within a bullâs eye about 4 feet square.
In 1900 Admiral Scott shared his innovation with a junior officer of the US Navy, Lt. William Sims, who then replicated Scottâs innovations and results on a US Navy ship. Sims advocated for this innovation, preparing and submitting to the Navy Department in Washington DC several reports describing the gun modifications made and the results obtained.
The response to Simsâ work came from the Chief of the Bureau of Ordnance. The response stated that continuous-aim firing is not possible.
The Bureau of Ordnance was responsible for approving the gunnery equipment then used on ships. Simsâ reports provided evidence that was contrary to the judgment of the Chief of the Bureau that the guns he had approved were the best guns possible for use in the US Navy. The Bureau Chiefâs reply stated that any problems with targeting must be the result of the gun operators, not the equipment. Only a direct appeal by Sims to the US President, who one could assume had no prior perceptions about naval gunnery, resulted in the implementation of this innovation.
The problem isnât simply that the Navy exhibited an aversion to change. Rather, the problem is that preconceptions held by the Navy bureaucracy blinded them to a solution to the gunnery problem that required objective evaluation of data that contradicted their prior beliefs.
What is thought to be an axiom may be an assumption
One of the common criticisms of risk management as it was practiced leading up to the financial crisis is that risk models for structured real estate securities assigned zero probability to outcomes in which prices fall. Perhaps that criticism is founded on 20/20 hindsight. Nevertheless, it is notable that within at least some models in use, it was not possible to ask what happens if house prices fall.
Once a paradigm is adopted certain questions no longer can be asked because they have no meaning within the adopted paradigm.
Consider the implications of this in the following illustration from geometry. Greek geometrician Euclid in 300 BC published a compendium of what was then known in geometry. So influential was this book that, speaking generally, Euclidâs book, The Elements, became the standard geometry resource for more than 1,500 years.
The Elements begins with 5 postulates and several definitions. A postulate, or axiom, is something taken to be self-evidently true (by every reasonable person) and therefore is something not requiring proof.
Euclidâs 5th postulate is different from the others in that mathematicians questioned whether its claim was self-evident.
Euclidâs 5th postulate says, draw two lines (in a plane) and then drop a third line so that it lies across the first two, if the two inner angles formed by that third line sum to less than 180 degrees than the first two lines must, if extended far enough, intersect.
That last bit, âextended far enough,â is where a problem arises. The âparallel postulateâ as it is called, is not self-evident because you may not be able to convince yourself that its claim is self-evidently true. How would you convince yourself if the sum of the interior angles were 179.999999 degrees or 180.000001 degrees for example?
If the 5th postulate is not self-evidently true, then it isnât an axiom. This is a big problem, because some of the theorems in Euclid relied on the 5th postulate for their proof. All would be well, if it could be shown the 5th postulate is derived from the other postulate. Unfortunately, no one was able to prove that was the case.
The conclusion drawn from all this effort is that the 5th postulate is actually an assumption. This is key for thinking about the impact of perceptions. Because the parallel postulate is actually an assumption, a question can be asked that could not have been asked otherwise. That question is, what happens if the âparallel assumptionâ is replaced with something more general.
When mathematicians experimented with relaxing the parallel assumption, they discovered (among other things) elliptical geometry (geometry on a sphere), which, as it turns out, describes the world in which we actually live.
Relaxing the parallel assumption revealed (among other things) that distance measured in Euclidean terms was different than distance measured in other geometries. In elliptical geometry distance is determined using something called the haversine formula (https://en.wikipedia.org/wiki/Haversine_formula), whereas in Euclidean geometry the familiar Pythagorean theorem (https://en.wikipedia.org/wiki/Pythagorean_theorem) is used for measuring distance.
Because Euclid mistook an assumption for an axiom, all who worked within the Euclidean paradigm were blind to the fact that different answers to geometrical questions might be possible.
It is a good idea to make explicit and test for self-evident-truthiness those preconceptions of what is axiomatically true in any risk management decision. The goal here is enable the risk manager to ask the broadest range of questions about the risky environment.
Euclidâs problem suggests another, perhaps more insidious, risk management risk arising from preconceptions about what is an axiom.
What was at first thought to be an assumption later may be treated as an axiom
When models are first developed the embedded assumptions are clear in the minds of both the model developers and early adopters. For a successful model, its users over time may begin to perceive the modelâs assumptions more as if they were axioms. While universal truths donât change, the validity of assumptions may. Assumptions must be brought out and reexamined regularly to reconfirm their appropriateness. This will not happen if an assumption, as a result of prior successes, is implicitly accorded the status of an axiom.
In the WSJ on January 14, 2016, Greg Ip criticized faulty modeling assumptions of âperpetualâ growth and âunlimitedâ demand for commodity inputs in China and âperpetualâ increases in oil prices supported by Saudi Arabian policies.
All assumptions are by their nature faulty with respect to some aspect of how the world works. The usefulness of assumptions depends on the trade-off, as perceived by the user, between the gain in problem simplification achieved by making the assumption and the damage done in abstracting from some potentially impactful aspects of the way the world works.
Ip was in fact deploring the use of these assumptions, because he felt they reflect, in the current environment, a poor trade-off between simplification and damage. By calling out this âperilâ, he was pointing out what can result when, once made, assumptions once made are not subsequently subjected to critical analysis.
When model assumptions are not actively re-examined, model users will show a lack of attention to disconfirming evidence. For example, it is easy to explain away portfolio risk model backtest exceptions as representing idiosyncratic or even expected behavior. The regulatory mandate that banks face for portfolio risk model backtesting and the penalties that can be imposed when models perform poorly act to enforce the scrutiny of modeling assumptions.
To mitigate this perceptual problem, assumptions should be stated explicitly and a formal process should be established for re-validation of assumptions.
Data do Not Speak for Themselves; We Speak for the Data
It is sometimes said that statistics donât lie, but, really, they donât truth either. It is a trick of argument to assign anthropomorphic properties to statistics, as doing so permits us to attribute objectivity to them. The attribution of objectivity of risk statistics disguises (even from ourselves, sometimes) both the subjectivity of choices made that lead to their calculation and the subjectivity of our interpretations that follow their calculation.
In a Value-at-Risk calculation, assumptions about the generating process for historical data (e.g., the model assumes normally distributed returns or constant volatilities) affects the values of statistics calculated using the model. Interpretations of the VaR results are both informed by our knowledge of the world (e.g., is this a risk-off environment) and colored by our preconceptions about the way the world works (e.g., is the market mean-reverting).
The impact of preconceptions on interpretation is illustrated by a papery by Bollen and Whaley (Journal of Finance (2009)). The authors look at the cross-sectional distribution of monthly hedge fund returns and find the distribution shows a smaller than expected frequency of returns around zero. They conclude this is âcaused at least in part by temporarily overstated returnsâ in order to keep or attract investor money. That is, they conclude hedge funds on average commit fraud by manipulating returns. In their paper Bollen and Whaley fail to consider a simpler, albeit less dramatic, alternative.
Hedge funds regularly report to investors the ratio of up months to down months as a measure of performance. Managers have a limited ability to affect this performance measure by altering the level of fund risk in response to recent performance (in other words create a feedback effect). A manager may choose to cut risk approaching the end of a reporting period, if the fund is in a small positive return position, in hopes of holding on to a positive month thereby. The manager is effectively giving up the chance of additional positive return in order to reduce the chance of a negative return at month-end. Analogously, a manager with a small negative return approaching month-end may choose to increase fund risk in the hope of moving the fund to a positive return by period-end. The observational evidence of this behavior is consistent with the data in the Bollen and Whaley paper.
While this alternative behavior reflects a problem with the incentives of the contract between managers and investors, it is not fraud. This simpler explanation does not come into consideration perhaps because there is at the ready a different interpretation more consistent with the popular, widespread perception of hedge fund managers as ethically suspect.
To guard against the effect of perception on choices made in data analysis and on interpretation of statistical results, it is worthwhile to consider (or at least explicitly acknowledge the possibility of) the impact on results of alternative methods of analysis and alternative interpretations of the results.
Pattern matching â Donât jump to Judgment
When you encounter a new situation requiring decision-making your mind is first engaged in an attempt to make sense of it. First attempts to make sense of a situation take the form of matching the available information with things you already âknow.â Finding a match within your existing knowledge accelerates decision-making. Your mind wants to jump to conclusions â all the time. Making quick judgments is valuable as a survival mechanism. Our brainâs ability to analyze unfamiliar situations quickly is an evolutionary mechanism that gives us a survival advantage that compensates for our relatively feeble physical abilities compared to, say, a mastodon or saber-tooth tiger.
However, the fight-or-flee decision so important when facing potentially life-threatening situations is not well adapted to more common situations requiring decision-making. Thus the automatic matching process also entails the risk of coming to the wrong assessment of the situation by rushing too quickly to judgment.
When matching, we focus on the information that is most familiar and most readily accords with your preconceptions about the way the world works. We discount or even ignore unfamiliar or discrepant information if it gets in the way of what would otherwise be a coherent construction of the situation. We may also unwittingly draw from our existing stock of knowledge to âfill-inâ bits of a picture that are completely absent from the current situation if doing so helps create coherence.
In risk management, identifying an emerging risk or a change in the risk environment or a breakdown in an investment thesis is a particularly big challenge to our pattern matching natures. This is because an established view, like other preexisting knowledge, closes the door to possible alternative perspectives on the environment.
We can mitigate this perceptual problem by deferring judgment.
Postponing judgment is something we have to do consciously, however. Institute a process that requires explicitly identifying and presenting evidence that is discrepant with the view that is attractive. Once you have adopted a view on a problem, look for disconfirming evidence, and discriminate against confirming evidence.
Finally, try to construct scenarios in which your story will break down and assess the robustness and relevance of your view based on the specifics of those scenarios. Reverse stress testing can be a helpful tool here, as in principle it can neutralize the effect of cognitive biases that might enter into the common way of designing stress tests.
Do Not Extrapolate except with Great Care
Data-driven models of uncertain futures can generate significant insights into a situation, but those insights may not apply to a situation that is outside the range of the data that drives the modelâs predictions.
On January 9 and 13, 2016, the Powerball lottery jackpots exceeded all historical experience, approximately $1B and $1.3B. Walt Hickey of fivethirtyeight.com discussed the importance of this for predicting ticket sales (and hence the also predict probability of a winning ticket being sold). Hickey has an econometric model to predict ticket sales based on jackpot size and the number of tickets sold . The parameters of his model are estimated using historical data on jackpot size and the corresponding number of tickets sold. Hickey knew his model might not predict well in the current situation.
â[B]y plugging $800 million into the model, weâd estimate 428 million tickets sold and a 77 percent chance of at least one winner,â he wrote.
âBut since this is the first time weâve had a jackpot this large, that estimate is based on an extrapolation of previous data. We really donât know, however, how lotteries behave at these levels. So thereâs a solid possibility that my estimate is off.
This type of situation can easily arise in a risk management context. A long time ago, I worked with bank examiners evaluating VaR model implementations at large banks. At one of these assignments, the bank, to speed up the VaR calculation, used a pre-calculated set of option prices based on a volatility grid with a pre-specified number of points on the grid. When it was necessary to find a volatility that was outside the range of points, they extrapolated â using a flat extrapolation (i.e., any volatility outside the grid would have the same value as the last grid point). A flat extrapolation is still an extrapolation, and thus not innocuous.
The bank could have experimented with several alternative approaches for extrapolation and for reference documented the potential range of prices that could obtain. Alternatively, the bank could have modified the grid so that the range of volatilities that were allowed for widened or narrowed based on the volatility-of-volatility.
In any case, the bank should have created a diagnostic report identifying the number and nature of options that were priced using extrapolated values. Diagnostic reporting is an effective way provide a feedback loop for gauging the accuracy of perceptions that have been built into model framework.
The world changes and assumptions about how the world works that are valid at one time may not be valid at others.
Our natural tendency to rush to judgment and our well-documented cognitive biases, such as the recency and availability biases, are powerful influences on our perceptions that can lead to misperceptions in a changing risk environment. It is essential to implement processes that help us maintain awareness of how our perceptions influence the way we have approached risk management problems. Better risk management decisions follow better awareness of these influences.