“…52 Concurrently, the majority of the most recent confocal Raman microscopy studies show a preference on using automatic, unsupervised true component analysis than the other spectral analysis approaches. 51,52 However, the other analytical approaches, either based on reference spectra or cluster analysis have been also widely used for Raman Microscopy. 37,38,69,70 It is known that the use of reference spectra can potentially over-simplify the obtained information, while cluster analysis could provide biased maps with higher sampling errors, as each cluster constitutes of a mini representation of the entire population based on simple random sampling.…”