<p>In stage 1, for each resident we choose the number of fingers () to acquire and whether ) or not ( to acquire the irises, based on the BFD and BID scores . We then observe the new similarity scores of the acquired biometrics, where the fingerprint scores are ranked according to the index . We compute the likelihood ratio and accept the resident as genuine if is greater than the upper threshold , reject the resident if is smaller than the lower threshold , and otherwise continue to stage 2, where both irises (if ) and additional fingerprints are acquired. Finally, we compute the likelihood ratio based on the biometrics acquired in stage 2 and then accept or reject the resident using the second-stage threshold .</p
