According to an aspect, there is provided an apparatus (2) for use in detecting malingering by a first subject in one or more physical and/or mental function tests, the apparatus (2) comprising a memory unit (10) and a processing unit (8). The memory unit (10) is configured to store information relating to a multivariate probability distribution, MPD, for a plurality of parameters, with each parameter relating to a particular physical and/or mental function test in a set of physical and/or mental function tests, the MPD being determined from one or more population test results, and each population test result relating to the performance of one or more tests in the set by a respective subject in a population of subjects and comprising values for the parameters relating to the one or more tests performed by the subject. The processing unit (8) is configured to receive a first test result for the first subject relating to the performance of one or more of the tests in the set by the first subject, with the first test result comprising values for the parameters relating to the one or more tests performed by the first subject； determine an indication of whether the first subject was malingering by comparing the values for the parameters in the first test result to the MPD； and output the determined indication.
