Once the characteristics of the sample have been measured we need to look at the distribution of the resultant scores. By distribution we mean how many members have got each of the scores on the scale. If we are measuring something that people have done and most people are in the middle of the range and a few are at the top and a few are at the bottom, we have what is called a normal distribution curve. If a distribution is skewed then more people will get scores at the top end or bottom end of the scale.

The most important statistical features of this distribution are:

• The mean – ie the average score
• The Standard Deviation (SD) or how the scores vary away (up or down) from the mean. A small SD means that scores are bunched up and the curve will have a sharp peak. A large SD will mean that the scores are spread.