Add spaces: Inordertodesignsuchanexperimentoptimallyitisnecessarytoknowthevariabilityoftheselectedresponsevariables.Thismeasureisusedinastatisticalpoweranalysisinordertocalculatethenecessarysamplesize.
In order to design such an experiment optimally it is necessary to know the variability of the selected response variables. This measure is used in a statistical power analysis in order to calculate the necessary sample size.