Statistical methods
Stata version 18.0-Basic Edition (StataCorp LLC, TX, USA) was used for
statistical analyses. Logistic regression was performed, and performance
of the investigated Raman system in HS prediction was evaluated through
serial binary classifications and corresponding Receiver Operating
Characteristic (ROC) analyses. As a non-parametric test, the
Mann-Whitney U test was a used to compare whether there is a significant
difference in the distributions of two groups of samples after
classification.