In 41 patients, all hyperfunctioning parathyroid tissue was resected at the time of surgery and confirmed by a corresponding decrease in the intraoperative postexcision rapid PTH determination as well as by subsequent normalization of postoperative serum calcium and PTH levels and resolution of clinical symptoms.
In other words, the standard deviation Ï (sigma) is the square root of the variance of X; i.e., it is the square root of the average value of (X â Î¼) 2. The standard deviation of a (univariate) probability distribution is the same as that of a random variable having that distribution.
The Variance is: Var(X) = Î£x2p â Î¼2. To calculate the Variance 1  : square each value and multiply by its probability. 2  sum them up and we get Î£x2p. 3  then subtract the square of the Expected Value Î¼2.