LEAST SQUARES SPARSE PRINCIPAL COMPONENT ANALYSIS: A BACKWARD ELIMINATION APPROACH TO ATTAIN LARGE LOADINGS

Sparse principal components analysis (SPCA) is a technique for finding principal components with a small number of non-zero loadings. Our contribution to this methodology is twofold. First we derive the sparse solutions that minimise the least squares criterion subject to sparsity requirements. Second, recognising that sparsity is not the only requirement for achieving simplicity, we suggest a backward elimination algorithm that computes sparse solutions with large loadings. This algorithm can be run without specifying the number of non-zero loadings in advance. It is also possible to impose the requirement that a minimum amount of variance be explained by the components. We give thorough comparisons with existing SPCA methods and present several examples using real datasets.