Developing & Using Test Norms to Compare Performance. A test norm is a set of scalar data describing the performance of a large number of people on that test. Test norms can be represented by two important statistics: Means and Standard Deviations.The most important measure in psychometrics is the arithmetical average or the mean. This is intuitive for many people.est norms can be represented by two important statistics: Means and Standard Deviations. The most important measure in psychometrics is the arithmetical average or the mean. This is intuitive for many people.