Closure Effects on Infrared Spectral Library Search Performance

Abstract
Closure is caused by normalization of a data set, and it affects any multivariate analytical method applied to that data set. Two common methods of normalizing infrared spectra (IR), to unit maximum absorbance and to unit vector length, are evaluated by measurement of library search performance. Search performance is evaluated, by the use of the Quantitative Reliability Metric (QRM), as a function of noise frequency and noise level.