Confirmatory Factor Analysis Model of the microarray study. The differences in gene expression related to cisplatin resistance are measured, using two-color microarrays, for four ovarian cancer cell lines (A2780, CP70, C30 and C200), which only differ in their degree of cisplatin resistance. The latent factors representing level of cisplatin resistance are depicted as a circle at the top of the figure. The squares represent the observed variables, e.g. the microarrays. The arrows connecting the latent factor and the arrays illustrate the loadings of the arrays on the latent factor. (In our model the latent factors do not load on the 'SelfSelf' hybridization, X1 (λx1* = 0)). The circles at the bottom of the picture symbolize the measurement errors. (This design was performed in triplicate with three independent cultures of the ovarian cancer cell lines).