Standard deviation refers to the extent to which scores in a distribution deviate from their mean or range. The standard deviation therefore involve substractinh theean from each score to obtain the deviation. The main properties of standard deviation includes;-
(a) Standard deviation takes into account all scores and responds to the exact position of every score relative to the mean of that deviation. This means that if one score is shifted further from the mean the standard deviation increase.
(b) Standard deviation is very sensitive to extremely score. For example if the obtained scores are 15, 16,18,24,20,70 the score of 70 is an extreme score.