If a variable y has (approximately) constant CV, then log(y) has (approximately) constant variance. So, use the standard deviation of the data.
---- begin included message --- Hi, I have a microarray dataset from Agilent chips. The data were really log ratio between test samples and a universal reference RNA. Because of the nature of log ratios, coefficient of variation (CV) doesn't really apply to this kind of data due to the fact that mean of log ratio is very close to 0. What kind of measurements would people use to measure the dispersion so that I can compare across genes on the chip to find stably expressed genes? something similar to CV would be easily interpreted? ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
