ICAR16 Intelligence Test

The 16-item version of the International Cognitive Ability Resource (ICAR), a public-domain intelligence test with four kinds of item: number series, verbal reasoning, matrix reasoning and three-dimensional rotation. No time limit; most people take about 8 minutes.

You get a total and a score on each of the four subtests, each with a percentile from the SAPA Project, where these items were given to about 169,000 online volunteers in 2010–17. SAPA gave each person only a random subset of the items, so the reference distribution is model-implied (a two-parameter IRT model with an empirically estimated ability distribution) rather than counted from people who answered every item; those who did answer every item scored higher than the pool, which is why the model is used instead.

The order of the items is drawn at random for each session: easiest to hardest, fully random, or in blocks by item type. We are measuring whether the order affects how many people finish.

Two changes from the original items: the “I don’t know” and “None of these” options are removed everywhere except the rotation items, where “none” can be right (guess instead), and the letter series are converted to number series (A = 1 … Z = 26). Both make the site’s version slightly easier than the one the norms were built on, so treat the percentiles as a little generous.