  In microarray experiments, it is often of interest to identify genes which
have a pre-specified gene expression profile with respect to time. Methods
available in the literature are, however, typically not stringent enough in
identifying such genes, particularly when the profile requires equivalence of
gene expression levels at certain time points. In this paper, the authors
introduce a new methodology, called gene profiling, that uses simultaneous
differential and equivalent gene expression level testing to rank genes
according to a pre-specified gene expression profile. Gene profiling treats the
vector of true gene expression levels as a linear combination of appropriate
vectors, i.e., vectors that give the required criteria for the profile. This
gene-profile model is fitted to the data and the resultant parameter estimates
are summarized in a single test statistic that is then used to rank the genes.
The theoretical underpinnings of gene profiling (equivalence testing,
intersection-union tests) are discussed in this paper, and the gene profiling
methodology is applied to our motivating stem cell experiment.
