Psychometric Questions

• How do I know which is the best test to use for a particular situation?
• How do I know which is the best norm group to use?

How do I know which is the best test to use for a particular situation?

If you are testing for selection, you need to familiarise yourself with the demands of the role you are selecting for. A well-written set of competencies is probably the best guideline, particularly if the competency definitions include clear guidelines for the behaviours that are sought.

You need to have the technical information on the tests that you are considering. A printed copy of the technical manual for the test (so that you can make notes), as well as the reliability, validity and norms information applicable to South Africa. The South African information is available elsewhere on this web site. You should also consider the range of reports that are available for the tests in question. You will still need to edit the report to remove irrelevant content and to add information that is specific to the particular application, but if reports are available that make the reporting task easier, that is a legitimate consideration in the choice of the instruments to use.

Pay attention to the description in the manual of the characteristics that can be expected of high and low scorers on the various scales for questionnaire type measures.

If you do not have the technical manuals, download them from www.psytech.co.uk. You may also need to download Acrobat Reader to print them if you do not already have it.

If you are still uncertain, contact the Psytech SA office and we shall be happy to assist you.

Remember, the choice of tests for a particular application is an action reserved for a registered psychologist

How do I know which is the best norm group to use?

In GeneSys, comprehensive information about the composition of norm groups is available if the norm was created using data that were "live" on the system at the time. Such norms are called Frequency norms. Of course, the system can only reflect the biographical composition of a norm group if the data were entered correctly in the first place. We strongly encourage users to enter this data, since it will only cause problems for you at a later stage if the data have not been entered.

In the Norms section for each instrument on this website, we have listed descriptive information about the South African norms that are available on our software

Please check the Downloads  section of this site regularly, newly created norm groups will be posted there. You can download the norms update files and update your system with the latest information.

When adding new respondents to the system, please take care to enter at least the respondents' home language and educational level.

When creating your own norms, it is very important that you should clean the data, eliminating any "dummy" cases that you may have used for practicing or experimenting with the system, and also eliminating any duplicate records that may exist in your database. If you are not comfortable doing this yourself, we can help.

One should use a norm group that is as similar as possible to the people you are evaluating. If you are running a large project, GeneSys makes it easy for you to create your own norm from the data you have collected. In such a case you do not need to worry about the suitability of the norm group provided your group is large enough.

If at all possible, use a South African norm group. South Africans score lower than UK groups on most of the ability tests, particularly the ones that are education-sensitive, like verbal reasoning, numerical reasoning and mechanical reasoning. Comparing South Africans with a UK group will yield low standard scores. The South African norms are labelled as such in the norm listing on the software. If the norm group is not labelled as South African, you may assume that it is a UK norm group.

We have now stopped distributing overseas norms with GeneSys, but for users working in the international assessment market, norms from other countries can still be made available on request.

If you need help in creating your own norm group or in choosing a norm group, feel free to contact the Psytech SA office.