Eleven million? or 22 million? A new Yale/MIT study estimates the illegal alien population in the US somewhere in the range of 16.5 to 29.1 million (for us statisticians, that’s 22.8 ± 6.3 million). That’s a margin of error larger than the entire population of Los Angeles (3.99 million). Worse yet, this estimate suggests that the Census Bureau’s annual American Community Survey report of 11 million is a seriously low-ball estimate. The Center for Immigration Studies is in the low-ball camp, but their argumentum ab auctoritate seems a bit shrill, and unwilling to admit to the possibility of systematic bias in previous estimates.
Not that counting is as easy as it appears. I regularly open my basic statistics classes with an audience-participation version of the classic Bouba-Kiki experiment, and collect response data by having two or more student volunteers count hands. Invariably, the student counts are not all the same. The confusion provides a “teaching moment” illustrating that the simplest measurement method is prone to variation.
Don’t believe me? If you’re a Windows computer user, download the freebie version of Wildlife Counts, and see how well you can count a static population of animals in a short time.