Square root biased sampling is a sampling method proposed by William H. Press, a computer scientist and computational biologist, for use in airport screenings. It is the mathematically optimal compromise between simple random sampling and strong profiling that most quickly finds a rare malfeasor, given fixed screening resources.
Using this method, if a group is
History
Press developed square root biased sampling as a way to sample long sequences of DNA. It had also been developed independently by Ruben Abagyan, a professor at TSRI in La Jolla, California, for use in a different biological context. An even earlier discovery was by Martin L. Shooman, who used square root biased sampling in a test apportionment model for software reliability.
Press' later proposal to use square root biased sampling for airport security was published in 2009. There, he argued that this method would be a more efficient use of the limited resources possessed for screening, as compared to the current practice, which can lead to screening the same persons frequently and repeatedly. However, use of this method presupposes that those doing the screening have accurate statistical information on who is more likely to be a security risk, which is not necessarily the case.