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Google Has Toughest Interview Process For Developers, But Not the Worst (getvoip.com)
An anonymous reader writes: A casual survey of candidates' reactions to the interview processes of the biggest tech companies in the world shows Google as having one of the most grueling hiring gauntlets in the sector — but Twitter's is perceived as the worst. The survey measured the amount of time candidature took, as well as the number of stages and the methods involved at each stage, and additionally estimated whether the job-seekers felt positive or negative about the procedure.
Genuine question, because I occasionally have to interview people: how do you interview people, and what sort of questions do you ask to try and work out if they are the right kind of person?
I'll give you Google's answer to this question, if you like.
Google does a series of four interviews, each with a different interviewer. All interviewers submit their responses to a hiring committee in writing. Each gives a hire/no-hire recommendation as well as scoring the candidate on a 1-4 scale (0 == if you hire this person, I'll quit; 2.5 == I have no opinion[1]; 4 == if you don't hire this person, I'll quit). Each interviewer also provides a detailed account of what they asked, how the candidate responded and what conclusions the interviewer drew. If the interview included writing code, the code is included in the feedback. The hiring committee, which includes no one who interviewed the candidate, takes the feedback from the interviewers and comes to a hire/no-hire consensus decision.
Each interview is nominally 45 minutes long, scheduled one hour apart, leaving 15 minutes between interviews for bio breaks, logistics, etc. Between the second and third interviews an additional "interviewer" takes the candidate to lunch. The "lunch interviewer" submits no feedback and answers the candidate's questions about the company, as well as giving them a break (and food).
For the actual interviews, each interviewer is instructed to focus on evaluating how smart the candidate is and how well they solve problems, not on how much they know. Basic CS knowledge is necessary because that's the language of the interview, and the candidate must know some programming language, but it doesn't matter which one.
Interviewers select their own questions to ask, but there are some criteria. First, the answers should not depend upon having some particular bit of knowledge. Other than basic CS knowledge, it's expected that the interviewer can provide the candidate with whatever information is required, though not necessarily all at once. It's good to provide partial information and see how the candidate goes about determining what else is needed, and obtaining the missing information. Similarly, answers should not depend on the candidate having some flash of insight. Such "aha!" questions say little about ability. The best questions are also progressive in nature; they start simple and build in difficulty and complexity as they're explored. This has a lot of benefits, not least that it allows weak candidates to feel like they had some success and walk away feeling like it was a good experience... even as the question showed the interviewer that the candidate isn't qualified.
Interview questions must also be calibrated. That is, the interviewer must know before going into the interview how well different kinds of candidates respond to the question, and must have a pretty deep understanding of the solution space. The calibration process begins by running peers through the question in a mock interview. That allows the interviewer to get a feel for what Google-caliber engineers do and do not see when looking at the problem and potential solutions. Different people are different, so it's recommended to have at least three or four peers help with initial calibration. Calibration is further refined by using the same question with many candidates. Google engineers have a small handful of questions they always use. They should always enter an interview armed with a well-calibrated question, plus a backup question or two in case the candidate is really outstanding and flies through the first question, or in case the first one turns out to be unsuitable in this particular case.
The interview begins with a few minutes of introductions/small talk to help the candidate relax. Most interviews consist of a single problem. The candidate is asked to devise an algorithm to solve it, describing the algorithm first verbally/pictorially, and then implementing the algorithm either on a w