Steve Kass

A recent numerical expedition led me to these summary statistics from a 2009 Pew survey on Religion and Public Life.

Looks like a typo to me. At a glance, the breakdown by age seems inconsistent with the aggregate result.

Most (about 85%) of the survey participants fell into one of the three oldest age groups, all of which favored gay marriage at a lower rate than the general population. The 65+ crowd, numbering 507, favored gay marriage at a rate a full 17 points lower than the rate for all ages combined. Although young’ens favor allowing Adam¹ and me (or Autumn and Eve) to get married legally, and they smile with approval at a rate almost 20 points higher than the rate for all ages combined, there are too few of them (only 283) to balance out the manier² old grumps and middle-aged semigrumps.

I have no reason to suspect the Pew folks of vulpigeration, so I tried to find an honest basis for these apparently contradictory figures.

Pew’s full report on survey question Q146a revealed one potential source of slop: the number under “Favor” seems be the sum of two individually rounded percentages: one for “Favor” and one for “Strongly Favor.” The actual survey instrument included both possible answers. Therefore, 39% could mean anything between 38% and 40%. Survey percentages are routinely rounded, but one expects 39% to mean somewhere between 38.5% and 39.5%.

Even allowing for extra slop, the numbers don’t agree. Here’s a tabulation (using the increased slop allowance) that gives the minimum and maximum numbers of favorers in each age group and (by summing) the minimum and maximum number of favorers among those in any age category.

According to these numbers, between 34.8% and 36.8% of 1,980 respondents would be cool with my marrying Adam legally.

According to Pew’s summary chart (at the top), though, between 38% and 40% of 2,010 responses, or between 764 and 804 people, answered “Favor.” That’s quite a bit higher than the breakdown figures show, and even if the 30 people in no age category (who presumably withheld their age or were under 18) all favored gay marriage, the maximum (and an unlikely maximum, because it would require all the rounding and missing information to be skewed favorably) number of favorers is 759.

As another plausible scenario, I calculated a Total percentage based on the age breakdown but weighted according to the actual histogram of age in the U.S. Still no dice. If anyone has an idea, let me know.

¹ For the record, I’m currently Adamless and available

² manier, adjective. Comparative of many; more numerous. To be coined presently. Many and numerous are synonyms; if things can be more numerous, I see no reason they can’t also be more many, or manier.