This manuscript presents a method for categorizing gamma-ray spectra as indicative of benign or threat sources. Reported here
is a method of spectral comparison ratios (SCR), which is useful in the targeted detection of specific gamma-ray signature
classes. SCRs discriminate between benign and target sources by comparing counts in broad energy bins that are pre-determined
using statistical discrimination criteria. The integral component of the SCR method is the location and interdependence of
the energy bins, and this work discusses the statistical methods used for choosing their locations along with decision criteria
that maximally separate targets from benign sources.