What Decades of Selection Research Tell Us About How Schools Should Make Admissions Decisions

Industrial and organisational psychology has been studying the validity of selection methods, their ability to predict performance in a role, since the early twentieth century. The evidence base is now substantial, and its implications for school admissions are largely being ignored.

In 1998, Frank Schmidt and John Hunter published a meta-analysis in Psychological Bulletin that synthesised decades of research on selection validity. Their analysis, drawing on data from tens of thousands of studies, produced a clear hierarchy of predictive validity for different selection methods. Work sample tests, structured assessments of the actual skills required, had the highest validity. General cognitive ability tests had validity coefficients consistently around 0.51. Structured interviews performed significantly better than unstructured interviews. Reference checks, years of experience, and many other commonly-used selection criteria had predictive validity that was surprisingly low.

School admissions does not map perfectly onto employee selection, but the underlying logic is the same: the goal is to identify which applicants are most likely to succeed in the environment they are applying to join. The research on what types of evidence predict that outcome is directly relevant.

The structured interview versus the casual conversation

One of the most consistent findings in selection research is the performance gap between structured and unstructured interviews. A structured interview, where specific questions are asked in a defined order and responses are evaluated against predetermined criteria, substantially outperforms a casual conversation in predicting subsequent performance.

Unstructured interviews, the type most commonly used in school admissions, where the assessor has a general conversation with the applicant and forms a holistic impression, have known validity problems. They are heavily influenced by first impressions formed in the first few minutes of interaction. They are affected by the interviewer's expectations, the similarity of the candidate to the interviewer, and numerous other factors unrelated to the candidate's actual potential.

This does not mean schools should abandon interviews. It means that an interview should be structured, criteria-referenced, and positioned as one input among several rather than the primary basis for a decision.

The persistence of cognitive ability as a predictor

Across the selection research literature, general cognitive ability is one of the most robust predictors of performance in cognitively demanding roles. The predictive validity is not perfect, it captures some of the variance in performance, not all of it, but it is consistent across contexts, cultures, and types of work.

For school admissions, this suggests that assessment of cognitive ability (which includes reasoning and applied thinking, not just acquired knowledge) should be a core component of the admissions process, not because it is the only thing that matters, but because it provides information that predicts outcomes in a way that many other commonly-used inputs do not.

Why non-cognitive factors still matter

The research on cognitive ability is not an argument for ignoring non-cognitive factors. Work by Nobel laureate James Heckman at the University of Chicago has documented extensively that non-cognitive skills, conscientiousness, perseverance, social competence, and approaches to challenge, predict life outcomes independently of cognitive ability and in ways that have significant practical importance.

For schools, this means that a student's disposition toward learning, whether they tend to engage with difficulty, seek feedback, and persist, is genuinely relevant to their likely performance, not just their raw academic scores. A well-designed admissions assessment captures a contextual signal about this disposition alongside the academic evidence.

The consistency principle

Perhaps the most practically important finding from selection research for school admissions is the consistency principle: the same process, applied consistently to all applicants, produces fairer and more reliable outcomes than variable processes applied by different people using their own judgement.

This is not an argument against professional judgement. It is an argument for structured professional judgement, where the framework is defined, the criteria are explicit, and individual expertise is applied within a consistent architecture rather than in its place.

See how Evalent builds these research principles into its assessment design.