Iterative piecewise linear regression to accurately assess statistical significance in batch confounded differential expression analysis

Abstract

Batch dependent variation in microarray experiments may be manifested through systematic shift in expression measurements from batch to batch. Such a systematic shift could be taken care of by using an appropriate model for differential expression analysis. However, it poses greater challenge in the estimation of statistical significance and false discovery rate (FDR), if the batches are confounded (collinear) with the biological groups of interest. Batch confounding problem occurs commonly in the analysis of time-course data or data from different laboratories. We demonstrate that batch confounding may lead to incorrect estimation of the expected statistics. In this paper, we propose an iterative piecewise linear regression (iPLR) method, a major extension of our previously published Stepped Linear Regression (SLR) method, in the context of SAM to re-estimate the expected statistics and FDR. iPLR can be applied to one-sided or two-sided statistics based tests. We demonstrate the efficacy of iPLR on both simulated and real microarray datasets. iPLR also provides a better interpretation of the linear model parameters. © 2012 Springer-Verlag.