Often we are asked questions, on the positive aspects of use of psychometric assessment. Say a psychometrically profiled role is being filled in by hiring candidates who match that profile, does that mean we end up hiring clones? Would it imply that such differences that contribute to attitudinal diversity are hindered when psychometric rules are used for making selection decision?
The simplest answer is both yes and no.
Yes because, theoretically, if a profile can perfectly describe a role, and if that exact profile is used to select for the role, there are likely to be commonalities between all such people selected by these means. However, assumptions made in this theoretical hypothesis are not well founded.
No because, it is almost impossible to find one profile that perfectly predicts performance in a role. Different people use different strategies to succeed at work. So only few variables would be valuable in differentiating the performance there.
It is also impossible to find people with exactly similar patterns of scores, even on 10 traits the chances of finding the same profile are one in a million!
Any psychometric assessment can not describe 100% of all individual differences. e.g. personality can only explain 16% of difference in performance, there is so much more even beyond measures of error that will cause people to be different even with largely similar scores.
Other levels of constructs like attitudes and values also interact with the profiles.
In summary, the impact of psychometrics on diversity is only a theoretical possibility. In reality or in practice, it is very unlikely if not impossible that psychometric instruments would reduce diversity of an organization. In fact, psychometrics can be effectively used to balance attitudinal diversity. E.g. in a prone to risk team, one would want to add a new member who is very cautious.