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.
Chi-Square Test for the Variance. where N is the sample size and s is the sample standard deviation. The key element of this formula is the ratio s/Ï0 which compares the ratio of the sample standard deviation to the target standard deviation. The more this ratio deviates from 1, the more likely we are to reject the null hypothesis.