\label{sec:intro} Currently much IQ data is gathered using commercially owned tests. One downside of this is that the tests are not freely available for use and one cannot freely adapt them to a new language. Our general aim is to change this by building public domain tests, translating them and validating them. We share all data and methods publicly so that anyone competent can check our results or reuse the data for other purposes.
We chose to add to the International Cognitive Ability Resource (ICAR) project which is described as:
... a public-domain assessment tool which aims to encourage the broader assessment of cognitive abilities in psychology and other social sciences and facilitate neuropsychological assessment in medical research and practice. The collaborators working on this project believe that the best way to achieve this aim is by making it easier for research scientists to employ flexible and unrestricted measures which have been well-validated against one another.
One of us has previously published one paper validating a Danish translation of the ICAR 16-item sample test[ref]. In the comments from the participants from that project and from another unpublished project using the same test, many users noted that the test took too long to complete and there was considerable attrition due to this. Thus, to enable the gathering of more data, it was important to develop an abbreviated version. The development of and testing of an abbreviated version of ICAR is the topic of this study.