Ask a Decision Scientist

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Q: Dear Decision Scientist,

At my company we're about to hire a key member of our leadership team. We have a number of very qualified candidates that we plan to interview. Can you give us some advice on how we should make our choice?

-Worried Hiring Manager

A: Dear Worried Hiring Manager,

It's great that you have so many qualified candidates for an important job in your company. But you may want to be careful about how you go about comparing the candidates you bring in for interviews.

Most of us make a pretty understandable mistake when it comes to hiring people. We write up a job description; we reflect on the organization's needs in the position and what it will take to be successful; we articulate those in terms of requirements; and we select a short-list of candidates based on an evaluation of which applications offer the best combination of those skills and capabilities.

So far, so good. But then we bring in these candidates for interviews, and things get a little more complicated. We learn, for example, that one candidate comes from a small farm in the Midwest and grew up working in the fields. We learn that another candidate started her own on-line company to sell handmade crafts. We learn that a third candidate happened to attend the same elementary school as one of our colleagues.

The problem with this is that much, if not most, of what we learn in an interview is not related to the skills we have identified as crucial for performing the job we need done. Scientists call this the difference between diagnostic and non-diagnostic information.

Say you're hiring a chief financial officer. Diagnostic information for that sort of job would include anything that indicated the quantitative skills of the candidates (their scores on the GMAT, say, or their grades in accounting or finance classes at business school); credentials that indicated their familiarity with the type of business you do (a person who had done financial management for a chain of hardware stores might be better equipped for working as a CFO for a construction company than, say, someone who had done the same job in a non-profit charitable organization); and evidence of their personal integrity.

Once you interview this person, you might find that they don't seem to dress well, or that they are members of the Appalachian Mountain Club, or that they're left-handed. All of those things may be interesting, but they probably don't have any bearing on how this person would perform in the job. They're non-diagnostic.

All of us tend to be swayed by non-diagnostic information, simply because we're pretty hard-wired to be social and to want to make human connections. But when the task at hand is to evaluate candidate for a job, the non-diagnostic information can start to crowd out the measures that are much more meaningful at predicting who will be successful. This is known as the dilution effect - the tendency of irrelevant information to crowd out information more pertinent to the decision at hand.

Don Moore, a decision scientist at the Haas School of Business at the University of California at Berkeley, has written a very helpful essay on how the kinds of information we receive in interviews can skew our hiring choices. You might want to take a look at it before structuring your interviews. At the very least you want to make sure your interviews all follow the same basic structure and are based on a list of questions designed to get a better sense of the specific skills you know are going to be critical to success in the job.

As you think about all this you might be saying-yes, but the interview helps us know who will make the best "fit" with our organization. That's important, of course, but we often overestimate the importance of "fit"-being willing to settle for a less-qualified candidate who makes us comfortable over a superior candidate who may seem, at least in a single interview, somewhat awkward or ill-at-ease. If you're hiring a person whose job it will be to represent your organization to clients, regulators, or other stakeholders, those skills may be very important to weigh. But beware of overvaluing "fit." You may end up missing out on the best candidate of all.