To Get More Signal From Coding Interviews, Stop Saying This Word
I have a confession to make: despite all of the scorn1 our industry heaps on coding interviews, I actually…kind of love them. I know: it’s pretty weird.
Although I’m rarely on the candidate’s side of the table, I’ve run hundreds of coding assessments, trained others, and reviewed scores of interview packets, all of which has led to spending a lot of time thinking about how get more consistent results out of them.
While most of my advice boils down to learning how to ask better questions and provide more robust hint progressions, one tip is so easy to follow that it’s almost shameful that I haven’t written about it before…
So what’s the trick?
Stop asking “why.”
But I’m getting ahead of myself…
When do we need to know “why”?
Much of the bad reputation for coding interviews is attributable to practices that have long since been discredited, like limited access to modern tooling2, problems with little relevance to the job’s actual responsibilities, and haphazard evaluation criteria.
Given that you’re reading about interviewing techniques, I’m going to assume that your organization at least has
a standard set of questions
an expectation that interviewers exlusively use those questions
clearly documented evaluation criteria that are tied to skills needed by the organization
Almost certainly, one of those criteria is going to be “communication skills,” and that means you’re going to need to get the candidate to explain some things3.
Often, your best opportunity to do this will come when you see the candidate do something interesting4. “How curious!” you’ll think to yourself, “Why did they do it that way?”
But here’s the important part: I need you to not say those words out loud.
Why not “why”?
While “why” questions may be commonly used to express curiosity, many, many folks have been culturally conditioned (from very early on!) to interpret them as rhetorical challenges:
“Why didn’t you do your homework?"
"Why are you getting home so late?"
"Why won’t you eat your vegetables"
"Why in the world would you do it that way?“
…and so on.
During normal, daily interactions, most of us are able to recognize the difference between “curiosity” and “challenge”, but an interview is far from an ordinary experience. In a high stress context—like an interview—your “why” is much more likely to be interpreted as, “I think you’re wrong.”5 And because the interview is already such a stressful situation, that sort of challenge will quite often trigger a fight-or-flight response.
Fight
Rather than provide an explanation, the candidate may stubbornly double down on their current approach, insist that their approach is correct, or otherwise try to bluster their way through without really answering your question. While this may be useful signal6, it isn’t the kind of signal that you were seeking.
Flight
Other candidates, having assumed that your “why” is a challenge, will also make the inference that you—knowing more about the problem—are challenging them because they’re wrong. Having concluded this, they may begin to search for a new strategy without explaining how they arrived at their earlier strategy.
In this scenario, it’s also possible to pick up some useful signal: particularly if they are on a fruitless path, you’ll be able to assess whether they can get to a better strategy with a bit of prodding. However, you’ll still be missing out on what you were trying to inspire, which was an opportunity for the candidate to demonstrate how well they communicate.
How to get an answer to “why”
So: we want the candidate to share their thought process with us, but asking “why” isn’t a useful strategy because it’s so easily misinterpreted. What do we do instead?
The solution that I’ve found most useful is to switch from asking a question to requesting an action:
“Talk me through the thought process that’s leading you to [implementation detail].”
“Can you walk me through an example of how [edge case] would be handled?”
“Help me see how you arrived at [conclusion].”
“Tell me about your reason for preferring [set of tradeoffs].”
By more explicitly describing the expected response, each of these forms is harder to interpret as a challenge. With less room for misunderstanding, more candidates will engage in dialog, providing you with the information you need in order to provide a fair evaluation.