| Abstract: |
Linear discriminant analysis (LDA) is frequently used for classi.cation/prediction problems in physical anthropology, but it is unusual to .nd examples where researchers consider the statistical limitations and assumptions required for this technique. In these instances, it is dif.cult to know whether the predictions are reliable. This paper considers a nonparametric alternative to predictive LDA: binary, recursive (or classi.cation) trees. This approach has the advantage that data transformation is unnecessary, cases with missing predictor variables do not require special treatment, prediction success is not dependent on data meeting normality conditions or covariance homogeneity, and variable selection is intrinsic to the methodology. Here I compare the ef.cacy of classi.cation trees with LDA, using typical morphometric data. With data from modern hominoids, the results show that both techniques perform nearly equally. With complete data sets, LDA may be a better choice, as is shown in this example, but with missing observations, classi.cation trees perform outstandingly well, whereas commercial discriminant analysis programs do not predict classi.cations for cases with incompletely measured predictor variables and generally are not designed to address the problem of missing data. Testing data prior to analysis is necessary, and classi.cation trees are recommended either as a replacement for LDA or as supplement whenever data do not meet relevant assumptions. It is highly recommended as an alternative to LDA whenever the data set contains important cases with missing predictor variables.
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