Thursday, July 9, 2015

Analytics for Dating: Local Gender Ratios?

The other day I heard a friend in her mid-30's say: "I used to be on, but they were always connecting me to guys in their 50's."  I thought this was weird, did Match have some kind of built-in "sugar-daddy" bias?  Maybe.  I remember reading the book "Dataclysm" last year,  pointed towards that type of behavior from guys on dating sites.  But could something else in the data (demographics) be to blame?

Today a light-bulb went off,  I had recently seen some weird age trending data for Kansas showing a proportional dropoff in people in their 30's living in Kansas.  Were the two related?


So in a quick conversation on twitter yesterday, I was led in the direction of how Kansas may be demographically different than the US in general.  I ran a few numbers, but one *anomaly* stuck out to me: Kansas has proportionately fewer people between 34 and 47 than one would expect based on US population data.  This double axis graph lays it out fairly well:

Could this be the root cause of my friend's issue, just more people in their 50's than 30's?  I thought maybe, but the effect size is fairly low (about a 5% differential). 

But what if the age anomaly was somehow gender driven, then maybe?  I broke down the numbers by gender.  No huge difference, though another trend emerged: the gender ratio (rate of males to females) is higher in Kansas in young adulthood than in other parts of the US.  And.. down the rabbit hole I went.


Quick background on gender ratio (or human sex ratio, yes I know the difference, but one matters to initial biology, the other to dating, so, we have to consider each).  The ratio varies over different human populations, but generally is about 1.06 at birth (more males than females).

The ratio steadily declines with age as men die faster due to biology and doing dumb things (shout out to my wife, yes I'll go to the doctor this decade).  Sometime in early adulthood the ratio approaches 1.0, and dips down significantly beyond that.  By 60 the ratio has fallen to 0.93, by age 80 it is around 0.7.

Although the ratio starts well above 1.0, the early deaths of males mean that population averages are generally less than 1.0.  For instance the ratios for Kansas and the United States as a whole are .984 and .967 respectively.  By that measure, there are more dudes proportionally in Kansas, so my friend should have no problems finding a guy?  (cue Levi getting slapped)


So what does this all mean?  If gender ratios vary significantly by geography, then what are some potential research questions and implications?

  • What underlying factors drive gender ratio trends?
  • What makes communities more female friendly versus male friendly?
  • Because gender ratio varies by age, are "older" areas inherently more female?
  • A dating implication? : Go to this high-ratio county to meet men tonight!!!
Out of curiosity, I mapped gender ratios by Kansas counties.  To moderate surprise, there was quite a bit of variation across the state.   Specifically, there were some clear heavily-male outlier counties. Here's the map by county.

I wrote a quick email to my friend, suggesting that she go live in one of the three heavily-male blue counties (Norton, Pawnee, Ellsworth).  Wait. Those outliers are actually un-realistically high. What is happening?

Prisons.  Those three rural counties are home to large male correctional facilities.  Correction email to friend: you should move to one of those three counties if you're into the dating prisoners thing.

On to the next tier of outlier male counties: 
  • Leavenworth: Prison.
  • Riley: Military Base.
  • Ottawa: Unsure, though I believe they have a jail that houses out-of-county inmates.
  • Two counties in far Southwest KS: Unsure, but they are surrounded by a statistically significant male leaning block.
For our out of state readers, Southwest Kansas has been defined by a massive influx of central-American immigrants over the past few decades.  These immigrants move here generally looking for work in meat packing and other agriculturally centered businesses in Southwest Kansas. Looking at the data, it appears that this movement for jobs in southwest Kansas has also impacted the gender ratio.  

Here's a map of Kansas counties by % Hispanic.  Note that the highly Hispanic area in southwest Kansas correlates nearly perfectly to the gender ratio outliers in the same area.


I started out trying to solve an anomaly on a dating site for a friend, and ended up looking at a lot of different issues.  

From a women seeking men perspective: I can say if women want to put themselves in areas with abundant men, then look at areas with high "traditionally male" labor demand.  Also prisons, if you're into that kind of thing.  I have a lower level (within Johnson County) analysis I will post tomorrow, that's a bit more informative, useful, and interesting.

Why are their few 30-something in Kansas: No great hypothesis here, but a few that are testable.

  • May not be a "dip" at 34, but instead two ongoing factors.  An aging native-Kansas population causing a hump to the right side of the distribution, combined with 20-somethings moving into the state to find work (hence male skew), such as Fort Riley and southwest Kansas. This would cause an apparent lack of 30-somethings, but is actually just an abundance in the high and low age groups.
  • Liberals will tell you that 30-somethings are leaving the state in droves to escape the Brownback administration and go to economically better states.  I will say that I've had several friends leave Kansas for Colorado in the past five years, so this is anecdotally possible.
  • Birth rate issues: haven't really explored this at all, but it could have shifted over that time period.

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