The first step is to determine the number of tasks evaluated and solved for each group of tasks. In the next step, the so-called standard value is calculated, i.e. the number of correct answers is converted into a scale with a mean value of 100 and a standard deviation of 10. This also takes into account the task difficulties determined empirically, so that the results of several test rounds in a test are comparable.

If a test participant has a standard value of 100, this will correspond to the arithmetic mean – always in relation to the total number of all participants.

Approx. 34 percent of all test participants score between a standard value of 100 and 110; the same number has values between 90 and 100. About 48 percent of the participants obtain values between 100 and 120; the same number applies to values between 80 and 100. Only approx. 2 percent of all test participants have values above 120 or below 80.

What is the reason for all this?

The conversion to standard values makes it possible to compare results from different groups of tasks directly with each other or with the result in the overall test, even if the individual groups of tasks contain different numbers of tasks.