Index score
An index score is a single number that combines several related measures, such as the answers to a set of survey questions, into one composite score. It summarizes a concept that no single question captures, like customer loyalty or brand health.
How it works
Building an index takes four steps. Choose the items that together represent the concept. Put them on a common scale, for example by converting each to 0 to 100 or to z-scores. Decide the weights, equal or based on importance. Then combine them, usually as a weighted average.
The OECD's handbook on composite indicators sets these choices within a longer ten-step sequence, from a theoretical framework to presenting the results, and shows that the choice of weights can change a ranking. Before relying on an index, analysts check that its items move together, often with Cronbach's alpha, where 0.70 is a common threshold, and they report the components beside the total so a change can be traced to its source.
Index = sum of (weight x score) for every component / sum of the weights
A worked example
Awareness 62, consideration 48 and recommendation 71, each scored 0 to 100, feed a hotel group's brand-health index with weights of 1, 2 and 1. The index is (62 + 96 + 71) / 4 = 57.25. Next quarter consideration alone rises to 54, moving the index to 60.25.
Related
Automate this in Pulse
Each component of an index can be a separately worded question in a Pulse survey, which lets a team see which component moved the composite.