#procreative pace

The Mother's Age is Now Factored In.

Recently, I received this Ask—

... and I typed up a whole response, explaining how difficult it would be to factor in Maternal Age, it's hard to quantify its impact on child spacing, etc., etc.

But, this Ask really got me thinking... The Master Spreadsheet that "runs" the Predictor actually has a lot, a lot of data, at this point. In the past, I've balked at the idea of incorporating Maternal Age, as I didn't think we had a large enough sample size. Our sample size is way bigger now.

So, I decided to try. After thinking it over, I decided to calculate the [Non–Firstborn, Non–Post Loss] Child Spacing Average for women within several Age "Bands"—Under 25, 25 to 29.99, 30 to 34.99, 35 to 39.99, and 40 and Over. (Age at Birth is the age used.) Then for each Age Band except Under 25, I created a ratio for that Age Band vs. All Prior Bands. The result is basically a Maternal Age Multiplier, which quantifies Maternal Age's impact on Child Spacing. Here are the numbers— (Note—You'll see "N" listed below; that's the sample size as of July 26, 2022. Data is drawn from All Predictor Families / Couples, and a large number of similarly "fundie" families, primarily In–Laws or In–Laws of In–Laws of Predictor Families. Families like the Vuolos, who aren't quiverfull, aren't included in the data.)

Under 25 N=49. Average Child Spacing (ACS) for this Age Band is 594.35 Days.

Age 25–29.99 N=115. ACS for this Age Band is 673.20. ACS for Younger Age Bands—in this case, there is just one prior Age Band (Under 25)—is 594.35. Ratio is 1.1327.

Age 30–34.99 N=105. ACS for this Age Band is 735.47. ACS for the 2 Younger Age Bands is 649.64. Ratio is 1.1321.

Age 35–39.99 N=76. ACS for this Age Band is 807.86. ACS for the 3 Younger Age Bands is 683.14. Ratio is 1.1826.

Age 40+ N=44. ACS for this Age Band is 936.14. ACS for the 4 Younger Age Bands is 710.61. Ratio is 1.3174.

This shows that, as suspected, ACS increases with Maternal Age... Now, can we say that age causes the increase? Absolutely not. It's just a correlation. But, it's a very interesting correlation, for sure!

From now on, the Predictor will incorporate Maternal Age using the Age Bands above. Here's how it will work: Procreative Pace (PP) is calculated the same way as before. (Average of All Non–Firstborn, Non–Post Loss Child Spacings.) That PP is then multiplied by Age Ratio / Multiplier that matches with the mother's forecasted age at the baby's birth. As an example, take Zach + Whitney Bates. Their PP, based on their data to date, is 717 Days. Whitney is Age 28.84, and expected to give birth again just before her 30th Birthday. So, we'd predict her next child's (Bates–Perkins #5's) Child Spacing by multiplying their PP by 1.1327, the Age 25–29.99 Multiplier. For her next birth after that (Bates–Perkins #6), she's expected to be in the next Age Band (30–34.99)—so, that Child Spacing is calculated by multiplying their PP by 1.1321, the Age 30–34.99 Multiplier. This is repeated for subsequent pregnancy, until the Fertility Cut–Off. All Zach + Whitney's Age–Adjusted PPs (AAPPs), based on data as of today, are as follows—

Age 25–29.99 717 Days (Their Baseline) * 1.1327 = 818 Days

Age 30–34.99 717 Days * 1.1321 = 818 Days

Age 35–39.99 717 Days * 1.1826 = 848 Days

Age 40+ 717 Days * 1.3174 = 945 Days

What's really cool about this is that, as more babies are born or more families are added to the Master Spreadsheets, the Age Band Ratios recalculate automatically. And, each couple's Age–Adjusted PPs will also recalculate automatically. So, it's very dynamically driven by the data.

Hopefully this makes sense to everyone, and y'all like it... Feel free to send in Asks of DMs with any questions or comments.

I'll do an ESOQ Update, factoring in Maternal Age, soon!

Childbearing Race:  Who is Outpacing Their Parents?

Fun Ask!  I’m going to limit this to Predictor Couples.  (So, I’ll compare Alyssa + John, but not John’s Siblings, to the Websters.)  Let's take a look...

Josie (Bates) + Kelton are outpacing Michael + Kristy Balka, whose Procreative Pace (PP) was 1,258 Days.  Josie + Kelton’s PP is 588 Days.  

None of the Bates Couples are outpacing Gil + Kelly Jo’s PP of 439 Days.  (Tori + Bobby come the closest, with a PP of 473 Days.)

With the exception of Carson + Carolina (PP 774 Days), each of the Bontrager Couples is outpacing Marlin + Becky’s PP of 674 Days.  (It is too early to tell for Allison + Jeremiah, but their Firstborn is due to arrive before Marlin + Becky’s— so, we’ll count that.  Why not.)  For those with >1 Child, here are their PPs—

Chelsy + John   470 Days

Mitchell + Bryn   636 Days

Josh + Cassidy   646 Days

Carolina (+ Carson) and Cassidy (+ Joshua) are both outpacing their parents—Curtis + Lauren Bowers.  The Bowerses’ PP was ~779 Days.  Carson + Lina’s PP is 774 Days, while Josh + Cassidy’s is 646 Days.

With a PP 494 Days, Joe + Kendra are easily outpacing the Caldwell Parents (Paul + Christina), whose PP is 1,039 Days, and slightly erratic.

None of the Duggar Couples are keeping up with Jim Bob + Michelle’s super–impressive PP of 472 Days.  (Joe + Kendra come the closest, at 494 Days.)

All of the Quiverfull Kellers (with >1 Child) are outpacing Mike + Suzette Keller, who had a PP of 898 Days.  (Nathan + Nurie are technically behind, since their Firstborn is due to arrive later than Mike + Suzette’s did.  But, it is still early on in their childbearing career.  We’ll see.)  Here are their PPs—

Esther + John   569 Days

Priscilla + David   636 Days

Anna + Josh   730 Days

While quiverfull (QF), Steve + Teri Maxwell had a PP of 669 Days.  Two of their sons are outpacing them—Christopher (557 Days) and John (490 Days).  Chris is married to Anna Marie Hamilton.  John is married to Chelsy Bontrager.  

With a 552–Day PP, Erin + Chad Paine were handily outpacing Chad’s Parents (Charles + Tammy Paine).  The Paine Parents’ PP was ~731 Days.

Whitney Perkins is an Only Child, so we obviously can’t compare her PP to her parents’.  (Fun Fact, though:  I recently learned that Whitney’s Father, J.C., was 1 of 11 Siblings!)

Jessa + Ben are outpacing Michael + Guinnevere Seewald.  Ben’s Parents’ PP was 847 Days.  Jessa + Ben’s is 679 Days.

Tori + Bobby are very, very easily outpacing Rob + Sheri Smith (Bobby’s Folks).  Tori + Bobby’s PP is 473 Days.  Rob + Sheri’s was 1,635 Days.  (They also only had 3 Children.)

Priscilla + David are definitely outpacing Brian + Sue Waller (David’s Parents).  Their PP was 820 Days.  Priscilla + David’s is 652 Days.   

Alyssa + John was outpacing Daniel + Sandy Webster (John’s Parents); it’s not even close.  Alyssa + John’s PP is 537 Days.  Dan + Sandy’s was 1,342 Days.   

Finally, the following In–Laws have a calculable PP, but it’s too soon to compare their offspring’s to it, since their offspring has 0 or only 1 Child, thus far.  Here is the list anyway, just for fun...

John + Cheryl Burnett   817 Days  (Abbie’s Parents)

Michael + Carla Clark   690 Days  (Travis’s Parents)

Ron + Jill Keilen   845 Days  (Brandon’s Parents)   

Jill + David Rodrigues   528 Days  (Nurie’s Parents)

Rob + Hilary Spivey   1,119 Days  (Claire’s Parents)      

Paul + Denese Stewart   1,395 Days  (Evan’s Parents)

Dwain + Lana Swanson   ~832 Days  (Lauren’s Parents)

Due to data gaps, I can’t calculate a PP for—George + Lauren Craig (Anna P.’s Parents), Kevin + Lisa Helferich (Praise and Jeremiah’s Parents), and George + Lisa Keyes (Esther’s Parents).

Finally...  I have no real data on the families of the following Predictor People

Bryn (Leppert) Bontrager

Karissa (Goering) + Mandrae Collins

Sierra (Baird) + Mark Dominguez

Anna Marie (Hamilton) Maxwell

Elissa (Frost) Maxwell

Melanie (Maher) Maxwell

Courtney (Harkins) + Christopher Rogers

John Shrader

What if:  The Dillards Kept Up The Pace Set w/ Sam

Procreative Pace (or Average Child Spacing) is one of the most important data points for the Predictor, since it drives Pregnancy Announcements—and, thus, Projected DOBs and ESOQ.  Here's the relevant data, as of March 20, 2020...

Working Pace for Individual Couples—

(Note—If a ‘+’ is listed after the pace, that means they are ‘late’ to announce their next pregnancy, and the Predictor is preemptively factoring in the delay, starting with their next next pregnancy.  As a result, late couples’ Procreative Paces will increase by ~1 Day every few days, depending on how many data points they currently have.)

The Duggars—

Joy + Austin   477 Days

Joe + Kendra   512 Days  (Note—Only one data point.)

Josiah + Lauren   622 Days  (Note—Based on Child 2 Multiplier.)

Jessa + Ben   649 Days

John + Abbie   732 (731.6) Days  (Note—Based on Child 2 Multiplier.)

Josh + Anna   732 (732.0) Days

Jill + Derick   919 Days+

Jinger + Jeremy   1,057 Days  (Note—Based on Child 2 Multiplier.)  

The Bateses—

Carlin + Evan   423 Days  (Note—Based on Child 2 Multiplier.)

Josie + Kelton   483 Days  (Note—Based on Child 2 Multiplier.)

Tori + Bobby   508 Days  (Note—Only one data point.)

Erin + Chad   552 Days

Alyssa + John   648 Days+

Zach + Whitney   691 Days   

The Maxwells—

John + Chelsy   510 Days  (Note—Only one data point.)

Chris + Anna Marie   557 Days

Nathan + Melanie   632 Days   

Joseph + Elissa   787 Days

The Kellers—

Esther + John   569 Days

Priscilla + David   653 Days

Anna + Josh   732 Days

The Bontragers—

Chelsy + John   510 Days  (Note—Only one data point.)

Josh + Cassidy   699 Days  (Note—Only one data point.)

Carson + Lina   807 Days+  (Note—Based on Child 2 Multiplier.)

Mitchell + Bryn   947 Days  (Note—Based on Child 2 Multiplier.)

... and, just for fun, let’s see how the Family Data stacks up—

Family Data—Average for Child 1

Bates Family   312 Days  (10.3 M)

Duggar Family   374 Days  (12.3 M)

Bontrager Family   396 Days  (13.0 M)

Keller Family   408 Days  (13.4 M)

Maxwell Family   458 Days  (15.0 M)  (Note—Nathan + Mel had a lot of fertility issues, at first, and their 1st Spacing isn’t included.  Including it would skew their Family Average massively to 803 Days.  Outlier!)

Family Data—Average for Child 2+

Bates Family   591 Days  (19.4 M)

Bontrager Family   605 Days  (19.9 M)  (Note—Only one data point.)

Maxwell Family   620 Days  (20.4 M)

Keller Family   627 Days  (20.6 M)

Duggar Family   650 Days  (21.4 M)

Family Data—Child 2 Multiplier  (vs. Child 1)

Keller Family   1.3083x

Maxwell Family   1.3323x

Bates Family   1.6834x

Duggar Family   1.7015x

Info, Please:  The Dillards’ Procreative Pace

You’re definitely not alone in being fascinated by Jill + Derick in particular.  Here is a summary of how they’ve been doing, so far, in the childbearing race…

The Predictor assumes Jill will take after Michelle in terms of fertility—and thus, ‘cuts off’ her fertility at 43 Years, 2 Months, 27 Days of age.  (That’s exactly how old Michelle was at Josie’s birth.)  Jill will reach that age on August 13, 2034.

Marriage and Israel—

Jill + Derick married on June 21, 2014.  Just 60 Days Later on August 20, 2014, they announced that they were expecting.  Due March 24, 2015, Jill was barely 9 Weeks Along, at the time.  (She was 64 Days—or, 9 Weeks, 1 Day—Along, to be precise.)  Israel was born on April 6, 2015, and was 13 Days Late.  (That’s a Duggar record!)  Labor and delivery were difficult.  After 70 Hours, Jill ultimately had to get a C–Section.  Israel arrived 289 Days into the Dillard’s marriage.

The Predictor didn’t exist in April 2015, but if it did, it would’ve expected Dillard #2 to arrive 527 Days—i.e., 289 Days + 50% (Honeymoon Baby) + 93 Days (C–Section)—after Israel.  Also, it would’ve expected Jill + Derick to announce the pregnancy at 64 Days Along, just like with Israel, and deliver 13 Days Late, just like with Israel.  Doing the math, here’s the date it would’ve predicted for those events—

Baby News   January 29, 2016

Due Date   September 1, 2016

Delivery   September 14, 2016

At this rate, Jill + Derick’s ESOQ was 14 Children Total. 

Samuel—

Unsurprisingly, that’s not exactly what happened. Jill + Derick announced their second pregnancy on December 20, 2016 (326 Days Late).  Due in “early July” 2017, Jill was ~80 Days Along, not 64 Days Along.  Samuel was born on July 8, 2017 by C–Section, after an unsuccessful TOLAC.  He was born 824 Days after Israel, when the Predictor expected a gap of only 527 Days.  So…  Basically, he was 297 Days Late.

After Samuel’s birth, the Dillards’ average child spacing shifted to 557 Days (or, (289 + 824) / 2) + 93 Days (C–Section).  Their typical Pregnancy Announcement shifted to 72 Days Along, while Jill’s average delivery shifted to 7 Days Late.  If we do the math again, the Predictor would’ve predicted the following dates for Dillard #3—

Baby News   September 16, 2018

Due Date   April 12, 2019

Delivery   April 19, 2019

At this rate, Jill + Derick’s ESOQ was 11 Children Total. 

Current Status—

As you know, the Dillards have yet to announce Pregnancy #3…  At this point, Sam is almost 2.5 Years Old, and still nothing.  Personally, I think this indicates that Jill + Derick are preventing pregnancy—and if so, good for them.  I’m sure it’s medically smart for Jill to avoid closely–spaced pregnancies after two really difficult births…  And, if they’ve just decided they’re done having children, even better!  Good for them for making that decision for themselves.

To support this theory, let’s calculate how ‘late’ Jill + Derick are to announce a third pregnancy.  In a very artificial sense, Jill + Derick’s Standard Deviation (or SD) for Child Spacing is 378 Days, since that’s what you’d get if you calculated it based on their two data points.  But, obviously, SD is better measured with a much larger sample…  Let’s just use a SD of 204 Days—i.e., the Child Spacing SD drawn from all of the Duggar Family data.  Here’s when Dillard #3 would’ve been announced, if his or her birth was Average, Average + 1 SD, Average + 2 SDs, etc.—

Average   June 21, 2018

1 SD Late   April 8, 2019

2 SDs Late   October 29, 2019 

3 SDs Late   May 20, 2020

Assuming a normal distribution, 68% of the data falls within 1 SD of the Mean, 95% falls within 2 SDs, and 99.7% falls within 3 SDs of the Mean.  Technically, you could argue that the large gap isn’t for sure anomalous until May 20, 2020.  We’ll see.  Maybe they’ll announce before then…

Even if they do, this large gap will have a major impact on their ESOQ.  Even if they announce today (December 29, 2019), the baby probably wouldn’t arrive until August.  The Samuel–to–Dillard #3 gap would be ~1,120 Days.  Factoring that in, their average child spacing increases from 650 Days to 744 Days.  And, if Jill has another C–Section, we’d add another 93 Days on top of that!  They’d have the following ESOQs—

w/ VBAC   9 Children   

C–Section   8 Children

Thanks for your ask, but please ask @duggardata this. She has a way more accurate procreative pace of most of these couples.