Measures of central tendency

What is a mean?

An average

Strength of the mean?

The most powerful measure of central tendency as it takes all the scores into account

Weakness of the mean?

• Can be distorted by extreme scores, so may be unrepresentative of the data set

What is the median?

The middle value of a data set

Strength of the median?

Unaffected by extreme scores, so a more appropriate measure when a data set includes anomalies and such

Weakness of the median?

Only takes into account one or two scores - the middle values, making it unrepresentative of the entire data set

What is the mode?

The number that appears most in the scores, the most frequently occurring value

Define bi-modal

2 modes in the sequence

Define multi-modal

2+ modes in the sequence

Strength of the mode?

Unaffected by extreme scores, so it’s a more appropriate measure when the data set contains these anomalies

Weakness of the mode?

Can be affected by the change in one score, making it unrepresentative

When is the mean used?

For interval / ratio data

When is the median used?

With ordinal level data

When is the mode used?

With nominal data