Multivariate statistical techniques discriminant analysis

A spectroscopic NIR imaging system, using a FPA detector, has been developed for remote and on-line measurements on a macroscopic scale. Multivariate statistical techniques are required to extract the important information from the multidimensional spectroscopic images. These techniques include PCA and linear discriminant analysis for supervised classification of spectroscopic image data (178). 

A study of VOC emissions from butter evaluated whether PTR-MS headspace measurements combined with a partial least square-discriminant analysis (a multivariate statistical technique) could be used to predict the origin of various butters that were produced in... 

We also make a distinction between parametric and non-parametric techniques. In the parametric techniques such as linear discriminant analysis, UNEQ and SIMCA, statistical parameters of the distribution of the objects are used in the derivation of the decision function (almost always a multivariate normal distribution... 

A high-throughput analytical technique such as NMR has promise of adoption to investigate the metabolite content of vegetables. This information combined with multivariate statistical analysis is expected to offer a conclusive and exhaustive idea of quality discrimination and prediction with high reliability for new samples. In the field of fresh cut fruits and vegetables, demands for quality determination are increasing over the past decade. 

The data processing of the multivariate output data generated by the gas sensor array signals represents another essential part of the electronic nose concept. The statistical techniques used are based on commercial or specially designed software using pattern recognition routines like principal component analysis (PCA), cluster analysis (CA), partial least squares (PLSs) and linear discriminant analysis (LDA). 

Besides regie.ssion analysis, there are other statistical techniques used in drug design. These fit under the classificalinn nf multivariate statistics and include discriminant analysis. 

The adaptive least squares (ALS) method [396, 585 — 588] is a modification of discriminant analysis which separates several activity classes e.g. data ordered by a rating score) by a single discriminant function. The method has been compared with ordinary regression analysis, linear discriminant analysis, and other multivariate statistical approaches in most cases the ALS approach was found to be superior to categorize any numbers of classes of ordered data. ORMUCS (ordered multicate-gorial classification using simplex technique) [589] is an ALS-related approach which... 

Classification and discriminant analysis algorithms are available with all multivariate statistical software packages. New or modified procedures are regularly being introduced and the application of such techniques and methods in analytical science is growing. 

Pyrolysis of food samples provides a large number of products, which, after detection by MS and analysis by advanced statistical treatment, can be used to compare different samples. The method is very rapid and does not require chromatographic separation or MS identification of the pyrolysis products. Pyrolysis MS, coupled with multivariate data analysis procedures, has been used to discriminate between cocoa butters of three different continental areas (Radovic et al., 1998). The technique could in some cases separate deodorized from non-deodorized cocoa butters and also show those that have had alkali treatment. The presence of non-cocoa fats did not affect the assay. 

The linear discriminant function is a most commonly used classification technique and it is available with all the most popular statistical software packages. It should be borne in mind, however, that it is only a simplification of the Bayes classifier and assumes that the variates are obtained from a multivariate normal distribution and that the groups have similar covariance matrices. If these conditions do not hold then the linear discriminant function should be used with care and the results obtained subject to careful analysis. 

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