Methods for determining the most likely composition of sample are disclosed. The methods can include: obtaining data from a sample, where the data includes a representation of a measured spectrum; determining a precision state of the representation of the measured spectrum; providing a plurality of library candidates; for each library candidate, providing data representing each library candidate, where the data includes a representation of a library spectrum; determining a representation of the similarity of the sample to each library candidate; determining the most likely composition of the sample based upon the determined representations of similarity of the sample to each library candidate; and displaying the most likely composition of the sample to a user.