I recently had a weird and negative experience applying for a job.

I went for standard the day-long interview, and answered a bunch of questions, and met a bunch of people, maybe 9. In one of the interviews, they asked me how I would approach some of the data questions they were working on, and I gave them some spur-of-the-moment advice. In one case I exactly outlined the approach they were actually taking. All this is fine, and to be expected. In fact I felt like the interview had gone well, and I had liked and been liked by most of the people I’d met.

Then, when I was about to leave for the day, they told me they wanted to send me “homework.” This is not something they had mentioned to me beforehand, but I was exhausted from the long day and I responded in a vague way, something like, “um, OK, well, I’ll take a look.”

When I eventually got it, the homework was very open-ended and very very hard. In fact I was guessing that it was probably an NP-complete problem, although I didn’t look it up (although I’m sure I could have, which is also weird). Moreover, it was directly relevant to the company’s business.

I felt like it was a fair question for them to have me work on if I had been hired, but it seemed too much to ask for me to work on it before then. Moreover, I was (and still am!) working very hard on my book, and I’d already given them a full day of my time. It seemed like they wanted me to give them free consulting in addition to applying for a job. I decided to write back to them and tell them I was very busy, and that I’d rather not do this homework “unless it was a dealbreaker.”

Here’s what happened next. First, the person who had sent me the homework told me it wasn’t a dealbreaker, and that I’d hear back soon. Then, nothing happened. Nothing at all. I didn’t hear from them for weeks, so I figured that was all the news I needed to know.

I finally wrote to a friend of mine who worked there just to say, hey, no hard feelings, I hope you’re well. By then I had totally given up on the job, but he was curious as to why. After telling him the story, the next day I got an email from his boss’s boss explaining that he had been waiting for me to go ahead and do the homework, and that he was disappointed I hadn’t been willing to. So it had been a dealbreaker after all.

So my question to you kind folks is this: when does an interview, and homework afterwards, become free consulting? What are the standards? Do you think I should have done the homework? Do you think it was unreasonable for them to ask of me? Or do you think it was OK for them to ask me but not OK for them to mislead me about whether it was a requirement?