Method of Parameter class (access via parameter$<function name>, where parameter is an object initialized by initializeParameterObject). Calculate variance of standard deviation parameter of lognormal describing distribution of synthesis rates
number of samples over which to calculate variance
mixture index to use. Should be number between 0 and n-1, where n is number of mixtures
If TRUE, should calculate variance using unbiased (N-1). Otherwise, used biased (N) correction
returns variance for standard deviation of lognormal distribution of synthesis rates