LESSON 6: MEASURES OF VARIABILITY OF GROUPED DATA

OBJECTIVES:1. Calculate for the variance and standard deviation of a given set of data2. Interpret the meaning of each measures

Standard Deviation is a number that indicates how the scores are scattered about the mean of the distribution. It is the square root of the VARIANCE.Recall:

Mean Deviation is the average of the distances of each value from the mean.

Example 1: The following list gives the number of hours by 4th Year students on leisure activities during a typical school week, find the mean deviation, variance, and standard deviation.

SCORESfXf*x

30 344

25 295

20 246

15 192

10 143

Example 2: SCORESfXf*x

16 184

13 155

10 127

7 93

4 61

GROUP ACTIVITY:

SCORESfXf*x

40 444

35 395

30 346

25 293

20 242