stochastic programsprobabilityand statistics it produces the additional plots in this case we see that the plot of coefficient of variation for the heads/tails ratio is not much different from the plot of the standard deviation this is not surprisingsince the only difference between the two is the division by the meanand since the mean is close to that makes little difference on the other handthe plot of the coefficient of variation for the absolute difference between heads and tails is different story it would take brave person to argue that it is trending in any direction it seems to be fluctuating widely this suggests that dispersion in the values of abs(heads tailsis independent of the number of flips it' not growingas the standard deviation might have misled us to believebut it' not shrinking either perhaps trend would appear if we tried trials instead of let' see it looks as if once the number of flips reaches somewhere around the coefficient of variation settles in somewhere in the neighborhood of in generaldistributions with coefficient of variation of less than are considered low-variance beware that if the mean is near zerosmall changes in the mean lead to large (but not necessarily meaningfulchanges in the coefficient of variationand when the mean is zerothe coefficient of variation is undefined alsoas we shall see shortlythe standard deviation can be used to construct confidence intervalbut the coefficient of variation cannot