Let us say I have an n element vector consisting of certain measurements with spikes that need to be located (n is small, say 5-7). My task is to locate all elements in the vector that are “much greater than the rest”. A method based on calculating standard deviations (or z scores) would work well if n were large, and the number of “large” elements were small. However, n is small, and the number of “large” elements can even equal n. So, a statistical method is not going to work.