Figure 2 illustrates a normal distribution of test scores with a mean of 100 and a standard deviation of 15. The standard deviation is an indication of the variability of scores in a population (Mather & Jaffe, 2002).nderstanding Standard Scores. The major purpose of standard scores is to place scores for any individual on any variable having any mean and standard deviation on the same standard scale so that comparisons can be made.
Note: True symptoms of PMS do not begin until after Day 13, any symptoms you experience earlier in your cycle may have another cause. However, you should still include any symptoms you experience on Days 1 to 13 on your menstrual cycle calendar.
Itâs PMS: If you have PMS, you may experience dysmenorrhea, which are cramps that you get 24 to 48 hours before your period. The pain decreases during your period and eventually goes away by the end of your flow.