Activity IDA: Calculating the Standard Deviation Although it takes a bit of time5 calculating the standard deviation of a set of scores is 31993111 nite easy. Just follow these steps. 1. List the scores in the rst column of a table, as shown in Table 1112. 2 Calculate the mean of the scores. 3. Subtract the mean 'om eaeh score to obtain the di'erenoe. 4. Square eaeh difference score, as shown in the last column. 5 Sum the scores in the last oolumn. 6 Divide this sum by the total number of scores in the distribution. 1 Take the square root ofthis number to obtain the stande deviation TABLE 113-2 Square the w 5 _ m = 15 225 ll] _ 2.} 2 ll] l 15 _ m = 5 25 2|] 20 = 0 [I 25 20 = 5 25 3|] 20 = 10 l 35 _ m = 15 225 Total = Till] Standard Deviation = square root of 71313:\"? = square root of 100 = Now: here is anew set of scores. 'What is the stande deviation of this set?r 2 3 III} 21} 35 35 35