The nondimensionalized standard deviation is used to identify genes whose expression levels may lie on bimodal distributions. (a) The behavior of for as a function of , where is the Gaussian distribution of unit standard deviation centered at . In this computations and . The inset shows the distribution when . It appears to contain two statistically distinct components. (b) The values of for the 11861 genes given at the TGCA site, in increasing order. Approximately 50 genes have values of significantly smaller than the rest.