An embodiment provides a method for measuring an analyte of a sample using a colorimeter, including: introducing the sample into a measurement chamber of the colorimeter, wherein the measurement chamber comprises an optical path from a light source to an optical sensor; identifying and waiting a sample settling period, wherein the sample settling period comprises a dynamic length of time, wherein the identifying comprises: measuring, using the optical sensor, a light throughput of the sample; and determining, based upon the measuring, the light throughput has reached a stable baseline; and obtaining a reference measurement of the sample when the stable baseline is reached. Other aspects are described and claimed.

An inspection method includes extracting a first similarity by comparing first data of a first optical signal with reference data of a reference optical signal, generating a first normal distribution of the first similarity, extracting a second similarity by comparing second data of a second optical signal with the reference data of the reference optical signal, generating a second normal distribution of the second similarity, and comparing the first normal distribution with the second normal distribution. The extracting of the first similarity includes deriving the first data of the first optical signal.