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  • Title: Class definition and mixture class definition by means of construction of convex hull boundaries: application to analysis for animal fat adulteration.
    Author: Thielemans A, de Brabander H, Massart DL.
    Journal: J Assoc Off Anal Chem; 1989; 72(1):41-7. PubMed ID: 2715135.
    Abstract:
    A visual classification technique based on the construction of convex hull boundaries in combination with a principal component analysis is described. This combined technique was evaluated in the situation in which a distinction has to be made between 2 pure animal fat classes and the corresponding mixture class. In the first instance, a principal component analysis is carried out to ensure the 2-dimensional and thus visual aspect of the technique. Convex hulls are then constructed in the 2-dimensional principal component plane to delimit the boundaries of the different classes to be defined. The effectiveness of the constructed hull boundaries in the definition of class-membership was investigated by means of the classification of different simulated test samples. The results show that, at least for the tested applications, the technique is valid, although some false positive classifications occur. The detection of outliers especially seemed to pose problems. Therefore, some propositions are made of how to refine the developed hull technique to enhance the classification results.
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