Due to differences in deposition pressure, matrix composition, substrate, and so on, latent ridge formation types, e.g., in particular ending and bifurcating ridge features, do not always reliably reproduce.   Specifically, the connectivity between pairs of corresponding ending and/or bifurcating ridge features from the same source sometimes disagrees.  For example, an ending ridge in one fingerprint sometimes appears as a bifurcation in the same fingerprint from the same source, and vice-versa. 

The T-Model does not ignore or explain away the connectivity disagreement between these most common Level II ridge features used by latent print examiners to effect fingerprint identifications, but instead subject's it to reduction based on reduced level of quality of agreement. 

The T-Model uses a reduction factor of 0.50 for pairs of “corresponding” ridge features that display connectivity disagreement.  Based on the theory that ridge feature shape, plays a (more or less) equal part to ridge feature position when defining the total weight that should be accorded to a ridge feature, a reduction factor of 0.50 was tested (e.g., see Fingerprint Comparison and Quality of Agreement Level II).  Based on validation study and tests against the largest and best friciton ridge look-alikes ever recorded, the T-Model proved successful in identifying these best look-alikes as insufficient to infer positive identification (e.g., see Error Rate in Terms of Best Look-alikes and Error Rates in look-alikes Calculated, and Validation Study).

Look-alikes frequently display connectivity disagreement between ending and bifurcating ridges and should not be casually dismissed, but rather subjected to reduction. 

Example

An ending ridge in a funnel in a latent impression corresponds in position to a bifurcation in a known impression. For purposes of conservativsim the lower weighted value for the ending ridge in a funnel is used, e.g., 10.  The pair of corresponding ridge features, e.g., at least in terms of orientation and positive,  displays connectivity disagreement and are therefore is subject to a connectivity disagreement reduction factor of .50 for a reduced level of quality of agreement.  As a result the quantitative-qualitative value for the pair of ending/bifurcating ridges is defined as 5, e.g., 10 x 0.50.