Read Part 1 — Interview Ups and Downs
How would you weigh a jet plane without using scales? How would you test a saltshaker? Count in Base negative 2.
I had a job interview a few weeks ago in which my chances appeared to hinge almost entirely on whether I could solve a particular puzzle. This was irritating to me many levels.
First, although I had heard that Microsoft (and now other firms) have been doing “puzzle” interviews in recent years, I had never before been forced to contend with one firsthand. I never plan to try for a job with Microsoft (or on Wall Street). I hadn’t realized these things were becoming the latest fad in interviewing.
Second, I don’t think my interviewer understood the “proper way” to manage a puzzle interview question — he didn’t seem well prepared (getting all of the necessary information was like pulling teeth) and he walked out of the room and left me alone to solve the puzzle. (Hmmm… maybe he decided to combine a puzzle interview with a “stress” interview… we’ll get back to that).
Lastly, I felt rather insulted that my chances of working for this company were being reduced to three short semi-technical questions and one really lame puzzle. The interviewer didn’t even look at my resume. Although I have 20 years of experience, it was obvious that the puzzle was the most important question I was asked. I didn’t solve it in the time alloted during the interview. Thus, the interview was over, thank you for coming, don’t call us…
I wasn’t interviewing for a job; I was interviewing for membership in a puzzle clique.
How would you move Mount Fuji?
I came home feeling frustrated and annoyed and convinced that I had just wasted three hours of my time. I started a discussion on a technical mailing list about interviewing techniques, puzzles, and my interview in particular. It was an interesting discussion and one of the list members recommended an even more interesting book — How Would You Move Mount Fuji? Microsoft’s Cult of the Puzzle by William Poundstone (Little, Brown and Company; 2003; ISBN 0-316-91916-0).
It’s a great book. I heartily recommend it for anyone who might be involved in an interview at any time in the future — from either side of the desk. Especially if you are a job candidate and have never been unlucky enough to experience a puzzle interview (or its evil twin, the stress interview) you need to know what to expect and how to react..
Apparently interview tactics have been changing in recent years, and not for the better! Poundstone says hiring interviews are “becoming more invasive, more exhaustive, more deceptive, and meaner.” Be prepared. Employers claim to use puzzles and “impossible questions” to gauge job candidate’s intelligence, imagination, and problem-solving ability. In fact, what they are really testing is the candidate’s interest in (and ability to solve) certain specific puzzles. The so-called “impossible questions” (e.g. How would you move Mt. Fuji?) may have give some clues to the candidate’s imagination, presuming an interviewer who understands how to interpret the results. Then again, they may not.
Some interviewers are using “stress” interviews because, they contend, “this is a high-pressure job and we need to know how candidates react to pressure”. That may be true, but does dumping a year’s worth of “crises” on a candidate to address in one day (as one company has done) really prove anything? Does the tactic of ignoring a candidate, or pretending to fall asleep during the interview (as other interviewers have tried), really have much bearing on real-world work-related problem solving?
How many of these questions and puzzles are simply a way to prove that the interviewer has the upper hand?
Why does Microsoft use puzzles?
Chapter 3 of How Would You Move Mount Fuji?… provides a discussion of Microsoft as a company and a culture. Having read this chapter (and the rest of the book 🙂 I have realized that the “puzzle cult” is quite appropriate for the Microsoft culture. However, I’m not convinced that most companies that follow along and decide to use puzzles for their interviews have quite the same reasons or justification (or even the knowledge of how to handle these interview tactics!).
Apparently Microsoft is, internally, a very competitive, game playing culture. People who enjoy solving these puzzles really <Bare more likely to fit into the Microsoft team. Furthermore, Microsoft does not (as is often presumed) use the puzzle & stress interviews on everyone. They do not, for example, use puzzles when interviewing senior management. As Poundstone says, “When a candidate has a track record, it’s almost always more informative and relevant to discuss that than to pose puzzles”.
Other companies, however, most likely do not have the same “puzzling” culture as Microsoft. Why, then, do these companies use puzzles and trick questions in their interviews? It may be that they simply want to follow a fad, even if they don’t fully understand it. Perhaps they see Microsoft as successful and believe that if they use the same interviewing techniques they, too, can be successful.
What puzzles does Microsoft use?
Microsoft’s interview questions were intended to be secret. It’s difficult, however, to keep a question secret once you start asking it of many people (who then go home and tell their friends). Several people have created web sites with lists of Microsoft interview questions. Other companies have started to use these sites as references for questions they can ask in their interviews. Unfortunately, the sites don’t always contain the answers; this can pose difficulties for companies that want to use the questions. 🙂
[Chris] Sells [maintainer of one such site] receives a stream of e-mail from other companies’ interviewers who want to “hire like Microsoft”. The problem? They need the answers that Sell’s site omits. “I always reply that if they don’t know the answers, then they shouldn’t be asking the questions,” says Sells. “This often pisses them off.”
Poundstones book spends half it’s nearly 300 pages providing in-depth discussion (and answers) for 53 sample puzzles and “impossible questions” that have been used at Microsoft and other companies. If you’re like me, you may enjoy reading the discussions of possible answers (and, in some cases, how to get the “right” answer). More competitive people may want to memorize the solutions, just in case the question is ever posed in an interview.
How Innovative Companies Ought to Interview
The last chapter in the book (right before the Answers section) discusses the actual good ideas that underly the puzzle interview. Poundstone says these good ideas are “too often mixed in with tricks, traps, power games, and hazing stunts. The goal of hiring the most capable people is frequently compromised by the interviewer.” In this chapter, Poundstone proposes a set of guidelines for how companies ought conduct interviews.
If you will be conducting an interview yourself, try to keep these guidelines in mind. If you are a candidate, on the other side of the desk, watch to see if the interviewer follows these recommendation. If he or she “breaks the rules”… do you really want to work for that person?
- The value of puzzles is in inverse proportion to the candidate’s expertise. — When a candidate has a track record, it’s almost always more informative and relevant to discuss that than to pose puzzles.
- Have an interview plan — Settle on a fixed set of questions and a fixed way of posing them; this is a way to minimize variables when comparing candidates.
- An interview is not an IQ test — You can’t ask enough questions in an interview to get a statistically valid sample.
- An interview puzzle is a filter to prevent bad hires — A good interview puzzle should be easy enough that you’re willing to reject anyone who doesn’t solve it.
[Personally, I disagree with this one guideline. I don’t believe that most interviewers are capable of selecting one really excellent question that is sufficient to reject a candidate flat out. The puzzle may produce a red flag; failure to answer may be a sign that you need to ask more probing questions in other areas. But unless you are admitting people to your special puzzle clique, I’d recommend being extremely wary of this guideline. – vlb] - Interview questions are only as fair as you make them — Avoid faulting people for not approaching a question exactly the way you would.
- Choose questions so that it doesn’t matter (much) whether the candidate has heard them before —Choose questions where the candidate can walk you through the reasoning he or she used.
- Challenge your first impression — There are jobs where first impressions should count. For most jobs, first impressions are less important or irrelevant. Ask questions where the answers may challenge the first impression.
- Avoid “questions with no right answer.” —These may be fun party games. They’re definitely not worth the time they take up in a hiring interview.
- Don’t do a “stress interview” — Stress interviews are adolescent power games that do little to identify the most suitable people for a job.
- Don’t pass notes — Having interviewers email each other with opinions during the interview process skews the results.
- Avoid deception, even the common “white lies” about interviews — Employment is a relationship of trust. Honesty is important whether the job candidate will end up working for you or not. No one should leave an interview feeling ill-used, ill-treated, or deceived.
Why are manhole covers round?
One of the anecdotes in the book seems, to me, to set the value of the puzzle interview in perspective:
In the early 1990s, Chris Sells was interviewing at a company called DevelopMentor. At the end of the interview, one of the company’s founders announced: “Okay, you’ve got the job. But I want to ask you one of the questions that Microsoft asks.” The question was, naturally: “Why are manhole covers round?”
“No problem,” said Sells. “I’ll answer that question if you answer this question: ‘Why do firemen wear red suspenders?’”
The company founder hadn’t a clue.
In case you don’t recognize it, Sell’s question isn’t from the Microsoft secret puzzle book… it’s a 4th grade schoolyard riddle.
Good luck on your next interview.
I find these new-fangled MicroSoft-inspired interview tactics to be very lame. If anyone throws this one at you, you’ll have had an opportunity to think about it ahead of time:
4 people are “escaping from zombies” (or whatever). It is night. They have 1 lantern between them. They reach a gorge, spanned by a log bridge. There are crocodiles in the gorge (or at any rate, it’s very deep). They need to cross the gorge before the zombies arrive (cross completely, then destroy the bridge).
As with all such puzzles, there are various artificial constraints:
- The people have 18 minutes before the zombies arrive.
- They must cross the gorge in _less than_ 18 minutes.
- Only two people can be on the bridge at the same time or it will not hold them.
- They need the lantern to cross; they can’t cross in the dark.
- It’s a long bridge and an old-fashioned lantern. You can barely see your feet; you can’t see very far ahead or behind on the bridge.
- It’s OK to be left alone in the dark on one side or the other.
- It gets more complicated (of course)
- Person A takes 1 minute to cross
- Person B takes 2 minutes to cross
- Person C takes 5 minutes to cross
- Person D takes 10 minutes to cross
(How they know this ahead of time is not provided by the puzzle gods).
Your job is to get everyone across the bridge, never more than two on the bridge at a time, always a lantern on the bridge, in under 18 minutes so they outwit the zombies
If you say “Oh that’s easy” (AND get it right too 🙂 you can go interview for this job…
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