Biometrics IPS, the Flat Earth Society and transformational cosmology

David Moss 2009
 

IPS may not have conducted any subsequent trials of flat print fingerprinting, but their cousins the UK Border Agency (UKBA) did start a six-month trial of biometrics based on facial recognition at Manchester airport in August 2008. 11 months later, no results have been published by UKBA [11].

When asked whether this technology works, instead of referring to the results of their own field trial, UKBA point to a report on the Face Recognition Vendor Test produced in March 2007 by … NIST [12].

This is another one of NIST’s computer-based trials, not a field trial. The conclusion drawn from the report by both UKBA and HOSDB is that biometrics based on facial geometry are now reliable enough for airport security [13]. No earlier report is cited. No later report is cited. This is the single report on which UKBA and HOSDB rely. Are they right to place so much confidence in it?

The trial uses eight different sets of sample biometric data (p.35). Two of them are sets of iris scan data. Iris scans are not on offer in the NIS and those results of NIST’s are therefore irrelevant. One is a set of three-dimensional face data, also not on offer in the NIS and so, again, irrelevant. Of the remaining five sets of data, four of them are taken from very few subjects – 257 subjects in the worst case, then 263, then 335, and 336 subjects in the best case. As any GCSE student can tell you, that is too small a sample for UKBA to be able to decide whether the technology would work for 60 million people in the UK.

Which leaves us with just one relevant sample dataset, of 36,000 subjects. And how well did facial recognition verify their identity? According to Figure 20 of the NIST report (p.46), at a false match rate of 0.01%, 100 times worse than Professor Daugman's working figure, the false non-match rate varies between 8% and 19%, depending on which supplier’s biometrics algorithm is used.

Once again, NIST provide no support to IPS or UKBA or HOSDB. A false non-match rate of between 8 and 19% does not sound like convincing evidence for the reliability of facial recognition as a biometric. Are UKBA really going to stop between 8 and 19% of passengers from boarding their flights? And remember that these figures emanate from a methodology which has already been discredited as a predictor of outcomes in the field [14].

There is one other piece of facial geometry evidence which it would be useful to see, and that is a report on the results of China’s 10 million faces test, an element of Operation Golden Shield. China, like the UK, is keen on using biometrics. That report is unfortunately not available.


Where there should be evidence, the NIS relies on wishful thinking. See p.5.

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