The notion of selecting appropriate candidates through the use of aptitude testing has been present throughout history. Examples of which have been present in the use of a rudimentary ability test in order to assess the abilities of prospective workers for the Chinese civil service. In 1832, the British east India Company adopted this system, bringing aptitude testing to the western world.
Through the works of Sir Francis Galton, statistical concepts such as regression, correlation and normal distribution were incorporated into aptitude testing. This allowed for intelligence to be measured and correlated with other variables. Since the work of Galton, huge advances have been made by notable psychometricians in the field of psychometrics, personality assessment and intelligence testing.
The popularity of psychometric tests and assessments throughout employment selection procedures was established by the formation of the well-known psychometric test provider SHL, by renowned occupational psychologists Roger Holdsworth and Peter Saville. SHL quickly became the leading publisher for psychometric tests worldwide and lead the way for psychometric testing in the workplace. Currently, almost all large organisations in the UK adopt psychometric testing at some point in their selection, recruitment and development processes.
How do they work?
Over the years the results of psychometric tests have been analysed against job performance and it appears that there is a moderate-strong association between high performance on the tests and high performance at work, suggesting that those who do well on psychometric tests, are also likely to perform better in the workplace. However, the association is not perfect, as it is possible to perform well on the tests and perhaps not do so well in an employment role, hence the importance of including a variety of stages throughout a selection procedure. The best psychometric tests are those with sufficient validity and reliability, meaning that they are fit for purpose and produce replicable results. This is important as for some candidates; the results of psychometric tests could lead them towards landing their dream job.
To determine the reliability of a psychometric test, there are a number of different methods. Commonly, candidates will be asked to complete the test twice with a substantial period of time in between completing each test. The scores from each are then compared to one another to determine if they are sufficiently similar, thus giving an indication of whether the scores are reliable. The internal reliability of the items within the test can also be determined through statistical methods. Validity refers to whether that which is being measured is actually the target of measurement and whether a test is fit for this purpose. For a test to be valid, it must first be reliable.
Candidates test scores are interpreted in relation to a norm group; this is a representative population comprised of individuals who have already taken the test and allows for scores to be compared to population benchmarks. The scores are transformed into percentiles, which give an indication of how the candidate has performed in relation to the comparison group. For example, scoring in the 52nd percentile would suggest that the candidate has performed better on the test than 52% of that population. The higher the percentile rank achieved, the better the candidate has performed.
Why use psychometric tests?
Psychometric tests that have sufficient reliability and validity tend to be the single best predictors of future job performance. For this reason they are a valuable asset to any selection procedure, as they offer an objective indication of the candidates’ abilities. Although it should be noted that they are most effective when used in conjunction with other methods of assessments, as they improve the validity of the process. For example, the combination of psychometric tests, competency based interviews and assessment centres produced higher predictive validity than either of these methods when used alone.