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Ask HN: What % of your job interviewees pass FizzBuzz type questions?

by tomx on 9/16/11, 2:03 PM with 117 comments

• by patio11 on 9/16/11, 3:45 PM

  For folks who doubt the numbers people are quoting here: remember, if half the pool can't program to save their lives, guess which half of the pool will still be sending out job applications next week.

  At a previous company where, for cultural reasons, lack of programming skill was not a barrier to being hired as a software engineer, approximately half of our software engineers could FizzBuzz. Of our outsourced coders, I'd put the number at one of the twenty I knew, and he would need extensive coaching to make it happen.

  Some of these folks were at least moderately productive at tasks which you and I do every day which theoretically happen in an IDE but do not require much abstract thinking, such as changing labels on UI elements, adding new columns to tables (by copy/pasting a line which worked and tweaking it until output matched expectations), and the like.

• by pixeloution on 9/16/11, 2:38 PM

  Just curious if you expect perfect code on a sheet of paper or give them an IDE and say go for it.

  As I remember fizzbuzz (print numbers 1 thru x, then fizz if divisible by 3, buzz if divisible by 5, fizzbuzz if divisible by both)

  I did it in a text editor in under a minute. Got two errors because I did it without thinking, fixed it, and had a working solution in 90 seconds. It's taking me longer to write this response.

  I can't imagine anyone who writes code daily who couldn't get this right in under 5 minutes given a text editor and a way to run the code, but I could imagine plenty of people who trying to do it on a sheet of paper who would make goofs. And most of those would make good employees.

• by ericb on 9/16/11, 2:21 PM

  In the actual interview, I find that most give up after spitting out some pseudocode. About 40% have reasonable psuedo code that makes me think they'd get there (but these half-answers don't give me enough confidence to give them a thumbs up).

  Actual code that works (and running it from a terminal), we are seeing only about 15% tops maybe lower.

  We have started sending a fizzbuzz-ish question, a relatively easy css question, and a word-problem about performance as pre-interview questions through recruiters. This has dropped our resume inflow dramatically and saved a lot of time, but that's depressing in a way.

  We are looking for a Rails or PHP dev in waltham (near boston) currently without a lot of luck. The job has a lot of pros, but probably doesn't do itself justice on-paper.

• by wavded on 9/18/11, 1:46 AM

  I failed FizzBuzz, I admit it. I was asked that as an interview question. I studied hard for my interview but I forgot about the mod operator and totally fumbled my way through the interview. I am now the Senior Web Developer and turned out to be a great asset to the company. But you wouldn't have known that from my FizzBuzz results. I also didn't have 'Computer Science' as a Major. Couple strikes. However they took a chance on me.

  Since then I've been able to interview others and I look for different things than FizzBuzz compliance. I want to see how they solve problems in general. I want to see if they have any passion for what they do. I want to see things they've developed.

• by corin_ on 9/16/11, 3:28 PM

  Can anyone explain how it is possible for people applying for these jobs to fail?

  I dabble in code, but am no where near the level I would have to be to do any job in this area, I mean seriously. Took my two minutes to do it with a pen and paper in PHP, same with in JS, same in bash scripting.

  How can anyone who isn't able to do this pretend to even have an interest, yet alone the ability to do the job?

• by buro9 on 9/16/11, 3:38 PM

  I think that the lower the percentage, the more you need to improve your screening prior to getting the candidate in. It's just wasting your time and theirs.

  I would love to say that you can tell from a CV whether or not they could pass FizzBuzz, but it's not true. I've interviewed MScs and PhDs that could not do FizzBuzz. Seriously.

  The phone screener is your friend.

• by elliottcarlson on 9/16/11, 3:24 PM

  I have used various interview questions, including FizzBuzz, factorials and other questions, and I would say the success rate I saw was about 20%. My personal favorite question is to have someone write a shuffle function without using any built in randomization functions - however most people give up, and others can't follow simple directions and wrap their head around the problem. This particular question had more of a 5 to 10% success rate.

• by ajuc on 9/16/11, 4:14 PM

  I have question to recruiters:

  if job requires "Hibernate" and I've used hibernate in my previous job, but have never configured it from scratch, only tweaked some models, wrote some EJBQL queries - does this count as "knowing Hibernate"? I've also never used Hibernate annotations, becasue we use hbm files, and we have templates to make the, so I'd have problems writing such file from scratch.

  Do you check knowledge of required libraries on the blackboard? Do you assume people should know all the corners of such libraries, or do knowing some things and wanting to learn more if it will be needed suffices?

  I use at work jboss, hibernate, jbpm, and many other technologies that are often mentioned in job offers, but I don't feel I can say I know them - only the parts that I needed to do the job. Is this considered not enough?

• by chollida1 on 9/16/11, 3:12 PM

  I've actually asked this question as a gentle warm up for people, and we achieve around a 90% success rate.

  On average it takes people around 5 minutes to do.

  We have people do it on a whiteboard to get them standing up and moving.

• by cantastoria on 9/16/11, 2:43 PM

  I'm curious what candidates are getting stuck on. Is it the testing for divisibility that's tripping them up?

• by DrJokepu on 9/16/11, 3:08 PM

  In my experience, about one in five (20%) people I get to interview can solve basic programming problems on a whiteboard (in their language of choice). It's really depressing.

• by ColinWright on 9/16/11, 3:37 PM

  We now insist on resumes being accompanied by the answers to set "homework." No answers, no interview.

  We get about half our interviewees unable to solve problems that are similar or easier during interview. Whether that's nerves/stress or simply an indication that they got someone else to do the homework for them we don't know.

  One candidate even phoned a friend during the coding part of the interview to get some answers. For some jobs he'd be hired, but not for most.

• by aplusbi on 9/16/11, 3:22 PM

  I've never asked FizzBuzz but I do regularly ask coding/algorithm questions. They are usually more difficult than FizzBuzz. I'd say around 80-90% can at least come up with a solution in 45 minutes with some help. Probably less than 10% can come up with a good solution entirely on their own.

  I attribute this to two things, first I think our phone screenings work well enough to keep out people who really can't do FizzBuzz, and second that I'm fairly generous during interviews. I often don't expect real code, sometimes I'm satisfied with just a discussion of the algorithm (no white board coding at all). I don't expect code to compile and I even let candidates use undefined "helper" functions (although I usually only allow that if I get the feeling that they could implement them if asked).

  * For those that are curious I have two favorite questions - print out all the permutations of a given (ASCII) string and describe a search algorithm for a sorted array that has been split in two and the two pieces have been swapped (i.e. - 4,5,6,7,8,1,2,3).

• by schulz on 9/16/11, 4:07 PM

  I did a ton of interviewing a few years ago ~ 100 interviews.

  I found about 10% nailed it right away with code that would compile and run. These were generally people who had been coding a lot recently.

  Half of the rest (say 45% of total) got close: Minor syntax errors, logic errors, stuff that an IDE/non interview situation would have fixed.

  45% just spaced. Couldn't right the for loops, conditionals. Couldn't write basic code.

• by spamizbad on 9/16/11, 3:14 PM

  4 candidates, 2 passed FizzBuzz. Oddly, the two that failed had a Masters in CS (albeit no BS in CS).

  Of those that passed: one had Masters in Library Science looking to change careers. The other was a fresh out of college CS major from Illinois State.

  Next batch, I think we'll add another trivial question: count the number of vowels (a, e, i, o, u) in a string.

• by wpeterson on 9/16/11, 3:43 PM

  The percentage of people who can complete a basic coding challenge during interview is more a testament to your phone screening than to the population of candidates.

  If you're not weeding out these people with a 10-15 minute phone call you'll waste a lot of your and their time.

• by albedoa on 9/16/11, 3:29 PM

  This post by Jeff Atwood might be of interest to you if you haven't read it:

  http://www.codinghorror.com/blog/2007/02/why-cant-programmer...

• by petercooper on 9/17/11, 10:54 PM

  Of those, about 50% can do FizzBuzz style questions. On paper, all of these ~10 people would be qualified to do the work

  If it's for a programming position, the "paper" is lying in this case. If someone is claiming to have experience or qualification in certain areas that they can't even perform basic operations in, they're fraudsters.

  It'd like trying to hire a surgeon and have someone turn up who doesn't even know what lymph nodes are. Dangerous and unhireable, but sadly a lot of employers put up with this sort of nonsense.

• by eftpotrm on 9/16/11, 2:51 PM

  That sort of thing specifically, never actually tested it.

  The last test I did help administer was for a VB+SQL job, and the first question was to write an example of a valid INNER JOIN. I'd say at maximum 25% of the candidates could do this.

  Improving SNR? I did once have a potential employer get me to do a time-limited online test. If you wanted you could always stick your questions into one of them, so you can at least do the fizzbuzz-level screening without calling them in and sitting them down.

• by lrm242 on 9/16/11, 2:52 PM

  How are you asking the questions? Good interviewers try to adapt to the person they are interviewing. Depending on how you're asking the programming question, you might want to think about changing it. If, for example, you sit back in your chair and ask someone to go to a whiteboard to write code you should consider that some people simply are not going to respond to that sort of method of answering, even if they are a brilliant programmer.

• by minikomi on 9/16/11, 2:49 PM

  Wow.. This is pretty astonishing. I know this is a majorly skewed, opinionated audience, but do people really not have that much of an interest in what they do?

• by davewasthere on 9/16/11, 3:45 PM

  Of people who get to the interview stage, I'd say around %75 at least successfully do the FizzBuzz question on our test.

  But we've cherry picked the CVs a little. And probably only interviewed 50 people over the past couple of years. (And hired 5)

• by sungura on 9/16/11, 4:02 PM

  I program a fair bit, have a few Android Apps in the market the problem I see with these type of tests is that I have a very hard time remembering syntax and would therefore have a hard time without an IDE.

• by acangiano on 9/16/11, 2:33 PM

  I mostly interview students for hands-on internships. I'd say around 10-20%.

• by mikereedell on 9/16/11, 3:27 PM

  While we don't ask FizzBuzz in particular we have a question my manager asks: If you could fold a piece of paper 50 times, how tall would it be (very rough ballpark figure)?

  Our success rate is surprisingly low.

• by gabyar on 9/16/11, 3:09 PM

  About 80%. Perhaps we're more vigorous with resume screening. Over the last 4 years of interviewing, I've become very good at resume screening.

• by mattdeboard on 9/16/11, 2:40 PM

  I wish we would run at least some kind of sample problem before hiring people. sigh

• by EponymousCoward on 9/16/11, 2:37 PM

  10-20% (pathetic really)

• by hga on 9/16/11, 3:01 PM

  The last time I was a part of this activity in a company (1997-8), using similarly rigorous pre-screening, we had about the same results, only 50% of the people we interviewed could program their way out of an (EDIT) wet paper bag.