Research methods - measure of dispersions 9

Measures of central tendency may not be the full picture on data and it is important to look at the variability of results also.

• two samples of data may produce the same mean or median, but have a different variability.
• description if data sold have a measure of central tendency and a measure of dispersion.

Measures of dispersion describe the spread, or variation of data around a centre value.

Methods of measuring the dispersion are:

RANGE - difference between the highest and the lowest number. Subtract the highest score from the lowest score.
SHOULD BE USED FOR basic measurement on inconsistent data. Inappropriate for extreme scores.
ADVANTAGE? Easy to calculate
DISADVANTAGE? Easily distorted by extreme scores

STANDARD DEVIATION - this is the most common measure of…