An index value is a conversion of an average value to make it easier to read and track over time.
The only difference between an index value and an average value is the scale on which it is presented.
Just like with average values, individuals who respond with options like "Do not know," "No opinion," or similar are not included in the calculation.
For example, 50% in an index value on a scale of 1-6 is the same as an average value of 3.5.
Feel free to calculate an index value using the CSAT calculator.
Why are index values used?
The reason for presenting index values is for educational purposes. Firstly, there's no need to consider the scale, and secondly, it's usually easier to understand that a change is 4 percentage points rather than decimals in an average value.
Presentation of index values
It is common to present index values with a color code that evaluates the result and makes it easier to prioritize which areas to work on. The color code may vary between surveys and subjects, but the example below is an established method for many types of surveys.
Calculation of index values
Here is an index calculation from a question with a scale of 1 to 6 and the option "Do not know/No opinion".
There are a total of 546 responses to the scale values, and the index value is 61%.
| Response option | Points per option | Number of responses | Points * responses | Description | Index value |