A2 - Psychology - Descriptive and Inferential statistics

Descriptive and inferential statistics 

Descriptive statistics

This is a summary of the descriptive statistics covered at AS, and their advantages and disadvantages. 

Measures of central tendency inform us about central (or middle) values for a set of data. They are 'averages' - ways of calculating a typical value for a set of data. An average can be calculated in different ways:

• The mean is calculated by adding up all the scores and dividing by the number of scores. It makes use of the values of all the data but can be unrepresentative of the data as a whole if there are extreme values. It is not appropriate for nominal data.
• The median is the middle value in an ordered list. It is unaffected by extreme scores but is not as 'sensitive' as the mean because not all values are reflected in the median. It is not appropriate for nominal data.
• The mode is the value that is most common in a data…