April 19, 2013

# Are Adam and Steve waiting out there?

I know many gay couples will want to marry quickly, but there *must* be a couple named Adam & Steve and we should totally let them go first.

Should we expect an Adam and Stephen couple? This is an opportunity to use public data and simple probability to get a rough estimate.

StatsNZ reported just over 5000 cohabiting male couples in 2006. That’s an underestimate of male couples, but probably an overestimate of those planning to marry soon.

I remembered seeing Project Steve, from the National Center for Science Education.  They collect signatures supporting the teaching of evolution from scientists named Stephen (after Stephen J. Gould) — they are currently up to 1268 — and make the point that under 1% of US males are named Stephen.

It turns out that they get this information from the US Census.  The most recent data is 1990 (and, of course, is US) so it’s not ideal, but it will give us a rough idea.  Stephen comes in at 0.54%, and when you add in Stephan, Esteban, Stefano, it still is no more than 0.6%.  Adam is 0.259%.

Under random assignment, then, there would be less than a 1 in 10 chance that there’s a couple called Adam and Steve living together in NZ, and even then they might well not be planning to get married.

[Update: Brendon correctly points out that I missed 'Steven', which is actually the most common variant. Apart from demonstrating that I'm an idiot, this doesn't change the basic message.]

Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

• Martin Kealey

• Thomas Lumley

That is left as an exercise for the reader. The calculation follows the same steps.

My guess is that the relative rarity of both Ada and Eve as names will mean a much lower probability, despite the larger number of female couples.

• Martin Kealey

Ada (& Adah) and Eve (& Eva, Evalyn, Yvonne, etc) look like they’d get paired off in about 1 in 240000 ♀♀ couples.

It seems that in addition to pairing off in one in 24000 ♂♂ couples, Adam and Steve (& Stephen, Steven & Stevie) will also be paired off in about one in 3.8M ♂♀ couples, but probably no ♀♀ couples (at one in 2.5B).

Allowing for more feminine alternatives for “Steve” could get about 100× more of both ♂♀ and ♀♀ couples.

(Very roughly, since some of the raw figures are 0.001% ± 0.0005%)

Male: