Gage reproducibility and repeatability methods do not account for a mix of random and fixed effects, nested factors, and repeated measures. Using a case study in fingerprint analysis, we propose a new method using linear mixed effects models to determine the decomposition of the variation components in a measurement system. The fingerprint analysis tests whether the measuring system for ridge widths is reproducible and repeatable. Using the new model and traditional measurement systems analysis metrics, we found that the current process to measure ridge widths is not adequate. Further, we discovered that it is possible to use a linear mixed model to decompose the variance of a measurement system.