Measures of Dispersion for
Grouped
MEASURES OF VARIABILITY FOR GROUPED DATA:
1. Standard Deviation - the positive square root of the variance which measures the
spread or dispersion of each value from the mean distribution. The formula to be
used in solving the standard deviation for grouped data is shown below.
2. Variance ( Mean Squared Deviation ) - is the average of the squared deviation
values from the distribution of the mean.
3. Quartile Deviation( QD ) - also known as the Semi - Interquartile Range is the
amount of dispersion present in the middle 50% of the values of the distribution, the
median plus one quartile deviation on either side encompassing 50% of the
observation. The formula for finding the quartile deviation is shown below.
Grouped
MEASURES OF VARIABILITY FOR GROUPED DATA:
1. Standard Deviation - the positive square root of the variance which measures the
spread or dispersion of each value from the mean distribution. The formula to be
used in solving the standard deviation for grouped data is shown below.
2. Variance ( Mean Squared Deviation ) - is the average of the squared deviation
values from the distribution of the mean.
3. Quartile Deviation( QD ) - also known as the Semi - Interquartile Range is the
amount of dispersion present in the middle 50% of the values of the distribution, the
median plus one quartile deviation on either side encompassing 50% of the
observation. The formula for finding the quartile deviation is shown below.
