One of the Important Assumptions Underlying the Use of Parametric

One of the important assumptions underlying the use of parametric statistics is that the sample is randomly selected from a normally distributed population. Consider a sample of N = 500. A sample mean and standard deviation is calculated and we find that the following is true. Between the mean and - 1 s there are 150 scores. Between the mean and +1 s there are 130 scores. Between - 1 s and -2 s there are 70 scores. Between +1 s and +2 s there are 82 scores. Beyond +2 standard deviations are 30 scores. Beyond - 2 standard deviations are 38 scores.