The process of collecting comparison data for an instrument is called standardization (normering in Swedish). Standardization is demanding work. A large amount of data, representative of the population in which the test is to be used, must be collected. A range of demographic variables (such as age, gender and educational level) must be taken into account for the instrument’s norms to adequately reflect the population and be used for comparison purposes.
In order to be able to interpret an individual’s result on a test, you have to put the result in relation to something. How high or low a result is can only be determined in relation to how others have performed. In order for the test to be widely used, almost all tests have standards. When you compare the individual result with the norms, you get a picture of how it compares to what other people with the same conditions, for example age, have performed. In some tests, there are different norm groups so that you can choose the comparison group that contains people of the same age as the person you want to compare. How many norm groups there are, and how they are divided, varies between different tests. How many norm groups you choose to collect data on depends on what conclusions you want to be able to draw about the performance of different people.
Our norm group originally consisted of approx. 3,000 people. A norm validation was then carried out where a sample of approx. 500 volunteers in the ages of 18 – 70, evenly distributed with approx. 80 people per 10-year interval. The subjects have completed the tests under similar conditions. Results have then been analyzed and adjusted resulting in a strengthened normal distribution and an age norm. An age norm is important as several of the abilities measured in the test are partly affected by age. It is also possible to compare results without taking age into account, which may be appropriate in specific cases where the capacity of a specific ability is considered particularly important.
A reference group is a group to which an individual or another group is compared. A reference group can be used as a complement to or instead of a norm if it is believed that the reference group is of higher value in specific contexts. The bigger the reference group, the higher the statistical power. Specific reference groups can be profiled on demand.