All in the Mind
Psychometric tests incorporate both ability tests and personality profiles, and are used by companies to get a better understanding of how good you would be at the job. Tests are not used to try to catch you out.
Ability tests measure your ability to carry out a specified intellectual task, such as verbal, numerical, spatial or diagrammatic reasoning. Each question has a right or wrong answer, although your scores will be compared with the scores of a large group. This means that while you may only score 40%, compared to the large sample group you may perform better than half of the group and it is this comparison which is used. Each test is usually timed, and while there may be around 60 questions to complete, you will not be expected to answer all the questions within the time limit.
Personality profiles provide a means of describing an individual's personality according to a number of criteria. It is important to remember that the purpose behind the exercise is to obtain a description of your personality, and that there are no wrong or right answers. However, be warned personality profiles include in-built lie detectors to ensure you do not try to pick out answers that you think the company wants to hear!