Square root biased sampling

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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.[1][2]

Using this method, if a group is times as likely as the average to be a security risk, then persons from that group will be times as likely to undergo additional screening.[1] For example, if someone from a profiled group is nine times more likely than the average person to be a security risk, then when using square root biased sampling, people from the profiled group would be screened three times more often than the average person.

History[edit]

Press developed square root biased sampling as a way to sample long sequences of DNA.[3] It had also been developed independently by Ruben Abagyan, a professor at TSRI in La Jolla, California, for use in a different biological context.[4][5] An even earlier discovery was by Martin L. Shooman, who used square root biased sampling in a test apportionment model for software reliability.[6]

Press' later proposal to use square root biased sampling for airport security was published in 2009.[1] 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.[2][3] 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.[7]

See also[edit]

References[edit]

  1. ^ a b c Press, William H. (February 10, 2009). "Strong profiling is not mathematically optimal for discovering rare malfeasors". Proceedings of the National Academy of Sciences. 106 (6): 1716–1719. doi:10.1073/pnas.0813202106. Retrieved 2009-11-28. 
  2. ^ a b "Square root bias and airport security screening". Homeland Security Newswire. 2009-02-03. Retrieved 2009-11-28 
  3. ^ a b "Researcher Proposes Statistical Method to Enhance Secondary Security Screenings". University of Texas at Austin News. 2009-02-03. Retrieved 2009-11-28. 
  4. ^ Abagyan RA, Totrov M (1999) "Ab initio folding of peptides by the optimal-bias Monte Carlo minimization procedure", Journal of Computational Physics, vol. 151, pp. 402-421.
  5. ^ Zhou Y, Abagyan R (2002) "Efficient stochastic global optimization for protein structure prediction", Rigidity Theory and Applications, eds. Thorpe MF, Duxbury PM (New York, Springer).
  6. ^ M.L. Shooman, "A micro software reliability model for prediction and test apportionment," Proceedings 1991 International Symposium on Software Reliability Engineering (IEEE, 1991), pp. 52-59.
  7. ^ William Press, "To catch a terrorist: can ethnic profiling work?", Significance, December 2010, p. 164.


Derivation: https://www.researchgate.net/publication/309809428_An_optimal_sampling_application_of_Cauchy's_inequality