how to identify that one gene have similar intensity value as other genes in the samples

Question

[kimberly]

please help me with this question

how one might take microarray intensity values calculated from
5 samples, and identify which genes have similar intensity values across all 5 samples. Assume that the
samples are collected at regular intervals during a process being studied, with the first sample from
day 0, the second sample from day 1, etc. Also, assume there is a separate probe on the microarray
for each gene

thanks alot guys!

Answer 1

[David Westergaard]

Yanai et al. defines a Tau index for tissue specificity T = (sum (1-intensity/max(intensity) ) / (N-1). It actually works quite well.

In your case you are looking for probes with a tau index near zero, indicating that they have equal expression values across all samples.