Pharmacy Practice

Pharmacy practice 456n to give the mean squared deviation (or variance). If the square rootof this is taken we get the standard deviation.Box 29.1 n, standard deviation and varianceIt can be seen that calculating a sample size is not easy. It requires judgement and priorknowledge about the distributions and effect size. The prior knowledge may come fromprevious research papers or, more often, has to be established by a pilot study.SIGNIFICANCEThere is a common and potentially misleading practice when describing results to refer tovalues of p