Explanation: Index

An index figure is useful in allowing us to compare data against a baseline average. Commonly included in Area Profile Reports (APRs) and in geo-demographic profiles.

Things to consider

An index value of 100 indicates that a result exactly matches the baseline average, an index of 200 that the result is twice the average, and an index of 50 that it is half the average. Broadly speaking, an index of less than 90 or more than 110 would be considered different enough from the average to take note of.

Ways of using this

The table below shows part of a Mosaic profile from a theatre. The table compares bookers to the theatre with the general population living within the catchment area of that venue. The index is helpful as it allow us to see in what ways these two groups of people differ.

Mosaic group

% of Theatre Bookers

% of 90 minute Catchment area population

Index

Professional Rewards

12%

8%

155

Suburban Mindsets

15%

14%

102

Small Town Diversity

4%

8%

57

Over-represented groups

We can see in the table above that 12% of theatre bookers belong to the MOSAIC group Professional Rewards. However, only 8% of all the people who live in the catchment area belong to this Professional Rewards group. This result shows us that the Professional Rewards group are over-represented in the theatre audience compared to the catchment area population. The index figure allows us to understand this in more detail. So, an index of 155 means that people from Professional Rewards theatre bookers are 55% more likely to attend the theatre a than the population of the catchment area as a whole.

Average groups

15% of theatre bookers belong to the Mosaic group Suburban Mindsets. 14% of people living in the catchment area belong to the Suburban Mindsets group. This tells us that the proportion of Suburban Mindsets attending the theatre and the proportion of Suburban Mindsets living in the catchment area is broadly the same. An index of 102 means that the theatre booker group is just 2% more likely to contain Suburban Mindsets people than a random sample of the catchment area population.

Under-represented Groups

4% of theatre bookers belong to the Mosaic group Small Town Diversity. However, 8% of all the people who live in the catchment area belong to this group. The Small Town Diversity group are under-represented in the theatre audience compared to the catchment area population. An index of 57 means that the theatre booker group is 43% less likely to contain Small Town Diversity people than a random sample of the catchment area population.