Facebook Data Scientist Interview Questions | Glassdoor

Facebook Data Scientist Interview Questions

Updated May 22, 2017
88 Interview Reviews

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Helpful (241)  

Data Scientist Interview

Anonymous Interview Candidate
No Offer
Neutral Experience
Difficult Interview

Interview

One HR interview, one takehome data challenge, one shared screen with SQL and one onsite with several 1:1 interviews. They check your coding skills and product sense via the takehome, your sql skills via the shared screen interview and machine learning theory as well as product sense during the onsite.
They let you choose the language for the takehome and onsite there is no coding on the board. So you just need to know one language (whichever you want, although I think they prefer R or Python) + SQL. No C++/Java/etc stuff and no CS algo questions.

Interview Questions

  • Data challenge was very similar to the ads analysis challenge on the book the collection of data science takehome challenge, so that was easy (if you have done your homework).

    SQL was: you have a table where you have date, user_id, song_id and count. It shows at the end of each day how many times in her history a user has listened to a given song. So count is cumulative sum.
    You have to update this on a daily basis based on a second table that records in real time when a user listens to a given song. Basically, at the end of each day, you go to this second table and pull a count of each user/song combination and then add this count to the first table that has the lifetime count.
    If it is the first time a user has listened to a given song, you won't have this pair in the lifetime table, so you have to create the pair there and then add the count of the last day.

    Onsite: lots of ads related and machine learning questions. How to build an ad model, how to test it, describe a model. I didn't do well in some of these.  
    19 Answers

Other Interview Reviews for Facebook

  1. Helpful (54)  

    Data Scientist Interview

    Anonymous Interview Candidate in Menlo Park, CA
    Declined Offer
    Negative Experience
    Difficult Interview

    Application

    I applied online. The process took 6 weeks. I interviewed at Facebook (Menlo Park, CA) in February 2017.

    Interview

    I applied online in late December and then spoke to a recruiter for about 15 minutes in early January. I was scheduled for an in-person interview in mid January where I interviewed with one data scientist in a 1:1 interview for an hour for the first round. Another recruiter then called me for a 30 minute prep for the 2nd round. The final, 2nd round interview was about 5 weeks later in late February, with 6 data scientists over 4 hours in the afternoon. I got an offer but it was for a lot less than I was expecting, and we couldn't bridge the gap enough for it to be worth it.

    Everyone seemed relatively nice, although I could tell that a lot of the questions are really designed to trip you up, like they want you to miss some detail or edge case. My advice would be to pay attention to every little bit of minutiae regarding the question, make sure you're staying on task, write on the whiteboard, and explain your thoughts. Industry word is that data science at Facebook is not what it once was and is more of a product data analyst role now, so make sure you're really into Facebook products because that's what you'll be analyzing.

    Also, I didn't get a single question about dice, cards, or any other brain teaser type questions. All these mentions of NDAs are missing the point of Glassdoor, people can be a little more verbose than "various questions". You can't trademark an interview question or claim it's a trade secret.

    Interview Questions

    • How would you measure the health of Mentions, Facebook's app for celebrities? How can FB determine if it's worth it to keep using it?

      If a celebrity starts to use Mentions and begins interacting with their fans more, what part of the increase can be attributed to a celebrity using Mentions, and what part is just a celebrity wanting to get more involved in fan engagement?  
      5 Answers
    • There is a table that tracks every time a user turns a feature on or off, with columns user_id, action ("on" or "off), date, and time.

      How many users turned the feature on today?
      How many users have ever turned the feature on?
      In a table that tracks the status of every user every day, how would you add today's data to it?  
      4 Answers
    • If 70% of Facebook users on iOS use Instagram, but only 35% of Facebook users on Android use Instagram, how would you investigate the discrepancy?   5 Answers
    • How do you measure newsfeed health?   2 Answers
    • If a PM says that they want to double the number of ads in Newsfeed, how would you figure out if this is a good idea or not?   3 Answers
    • We have two options for serving ads within Newsfeed:
      1 - out of every 25 stories, one will be an ad
      2 - every story has a 4% chance of being an ad

      For each option, what is the expected number of ads shown in 100 news stories?
      If we go with option 2, what is the chance a user will be shown only a single ad in 100 stories? What about no ads at all?  
      7 Answers
    • How do you map nicknames (Pete, Andy, Nick, Rob, etc) to real names?   3 Answers
    • Facebook sees that likes are up 10% year over year, why could this be?   4 Answers
    • How many high schools that people have listed on their profiles are real? How do we find out, and deploy at scale, a way of finding invalid schools?   4 Answers

  2. Helpful (23)  

    Data Scientist Interview

    Anonymous Interview Candidate
    No Offer
    Negative Experience
    Average Interview

    Application

    I applied through a recruiter. The process took a week. I interviewed at Facebook.

    Interview

    This is about the interview for 'data scientist - analytics.' There are other data scientist positions in facebook such as research scientists or data scientists in core science, and the interview process is different for data scientist-analytics. Please keep that in mind.
    Anyways, my interview is a bit different from others in that I didn't have a phone chat with the recruiter or anything like that. I just got an e-mail from one of the recruiters (University recruiters... I was a full data scientist at other company back, and I still am now) that I was selected for a video interview for 'data scientist, analytics, INTERN,' a position that I never applied for, and it asked me to fill out questionnaires and to confirm my availability on Feb 20st (not sure about the exact date, but close). So I told the recruiter that while I'm excited about the interview opportunity at the facebook

    1) I am already a full-time data scientist at another company
    2) I graduated 3 years ago
    3) I am only interested in the full-time job

    and then I got an e-mail saying that I would be considered for the full time data scientist job. I was like 'sure' and we set up the video interview on that day. No phone chat with the recruiter whatsoever, just an e-mail description of what the interview would be like along with the link.

    The interview was two parts: SQL and product question. Before I dive into questions, I just wanted to say that I had interviews with a bunch of other firms (Microsoft, Amazon, Google, Apple, etc) in the past, and this was one of very few times when no stat/math questions were asked at all during the technical phone interview. The job description seems to mention that the statistical modeling skill is required, but from the way interview is structured, I can get the feeling that the importance of SQL coding skill and product sense far outweighs the level of the interviewee's stat/math knowledge. This seemed more like a business intelligence analyst type of role, not the data scientist role that I envisioned at a company like facebook (Again, I'm only talking about the data scientist - analytics position. Research scientist of data scientist in core science role could be really research-oriented and fun).

    Now, the SQL question was just that given a table of users where each user can take a specific action (Accept, reject, etc) on the other user on a certain date, how would I track the acceptance rate over time. Again, this is just a simple SQL coding, and you can easily do it as long as you know how to do INNER JOIN on different tables.

    For product question, it asked for a feature that I do not remember and how would I test whether adding that feature would be beneficial for the company. Just a simple a/b testing question, but you really have to hone your product sense and be able to look at it from various angles. Would the user be satisfied with the feature? Would the feature take up too much space that could be used otherwise (ads or other pages)? and so on.

    Overall, I think I did well, but again, that's just my feeling. However, at least, I am sure that I got the SQL part done correctly and fast enough. After the interview, I asked the interviewer how long it would take to hear back, and he said probably a couple of days, but hopefully not more than a week. However, here's a twist. I got a rejection e-mail, AN HOUR later (never really got the reply back this fast in my life after phone screening), and it said I would not be considered for "Data Scientist, Analytics, University Grad" position. UNIVERSITY GRAD! from the same recruiter (university recruiter) who initially e=mailed me about the internship opportunity.

    That position only applies to those graduating in 2017, and I made sure to the recruiter that I am no longer a university student. I replied back asking that why the position says university grad, and guess what? I never got the reply back.

    Either way, in terms of the interview questions, the role seemed to put too much focus on SQL (which you can seriously learn in a day) and product sense (a quality that's highly valued for business intelligence analyst role). Also, in terms of how the interview progressed, it was totally and utterly unprofessional (shooting me an e-mail that I would be interviewed for an intern, a position that I never applied for, and giving me just one day and asking me to confirm my availability on that day, not even giving me flexibility on which date to choose from, and rejecting me one hour after the interview for the position that is still not what we agreed on).

    I have nothing against Facebook. I still think it's a great company with amazing culture and perks, but I really don't think I'll recommend any of my friends to apply for data scientist analytics roles for facebook.


  3.  

    Data Scientist Interview

    Anonymous Interview Candidate
    No Offer
    Positive Experience
    Difficult Interview

    Application

    I applied through a recruiter. I interviewed at Facebook.

    Interview

    A recruited reached out to me and I had a call with her. This was followed by a technical screening with a data science manager. The last step was a full round of interviews onsite.

    Interview Questions

    • They asked SQL questions, probability and product analysis   Answer Question

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  5.  

    Data Scientist Interview

    Anonymous Interview Candidate
    No Offer
    Neutral Experience
    Difficult Interview

    Application

    I applied through a recruiter. I interviewed at Facebook in May 2017.

    Interview

    Recruiter conversation and phone screen, one phone screen via video call.
    At first I was pleased because the recruiter sent a detailed preparation guide and I had a few weeks to prepare. I spent some time preparing nearly every day, making sure I was well versed in R, which was the language that I requested for the phone screen.
    The recruiter emphasized that product sense was important, so I spent time thinking and reading about metrics necessary to evaluate products and how that may be applied to Facebook.
    In the end, I think I would have been better off without the interview preparation guide, as it turned out to be completely misleading.
    The interview contained no probability questions, even though that was mentioned as part of it, and no product sense questions. There was only one fairly straightforward data engineering type question.
    The rest was simply SQL questions, even though I had requested R as the language. I was able to use R to answer the SQL question, and then for the second follow-up questions switched to SQL, but really the type of question would be best answered with SQL.
    The interview guide said that if you requested R, then they would be testing dplyr/apply functions, but that wasn't really true.
    The SQL question was not straightforward, but fairly challenging. I was thrown off because I was expecting a data analysis question using R, and I was a bit nervous under pressure. I was able to answer the questions, but not without stumbling a bit.
    The whole process was frustrating because I write fairly complex SQL questions often as part of my job, and have never had a query I couldn't figure out. But under the pressure of the interview, I didn't perform spectacularly. I wish I had not spent time on the other parts of the interview prep and just focused on SQL, and I probably would have been more successful. So beware the prep guide may lead you astray.

    Interview Questions

    • SQL question
      One basic data engineering related question  
      Answer Question

  6.  

    Data Scientist Interview

    Anonymous Interview Candidate
    No Offer
    Neutral Experience
    Average Interview

    Application

    I applied through college or university. I interviewed at Facebook in April 2017.

    Interview

    Was contacted by university recruiter. Very drawn out process, took several weeks just to get 2 phone screens in. First screen was technical, all SQL. Second was basic a/b test question, that I did not pass. Interviewers did not seem particularly engaged.

    Interview Questions

    • Other reviews go over the SQL stuff pretty well   1 Answer

  7.  

    Data Scientist Interview

    Anonymous Interview Candidate
    No Offer
    Negative Experience
    Average Interview

    Application

    I applied through an employee referral. I interviewed at Facebook in April 2017.

    Interview

    The person came in online 5 minutes late, not even mentioned his name. Also, a different guy showed up from the one recruiter mentioned (I did look up online before for a picture) and on top of that recruiter modified the interviewer twice. The interview was so mechanical, not testing the smartness at all. It was like - I ask a question, you give me an answer, just the answer I have on my sheet - not a creative one.

    For the god sake, ask some smart questions and help the candidate to express their real skill and bring in or analyze the candidate's creativity. This is only regarding one DS Manager I interviewed with, maybe other facebook folks are not this weird.

    Interview Questions

    • Give me an analytics project you have done?   1 Answer

  8.  

    Data Scientist Interview

    Anonymous Employee in Menlo Park, CA
    Accepted Offer
    Positive Experience
    Average Interview

    Application

    I applied through a recruiter. I interviewed at Facebook (Menlo Park, CA) in April 2017.

    Interview

    The hiring process is very clear and well done. Each step of the way, recruiters will walk you through what their expectations are and provide you with sample questions.

    You set your own schedule so you can make sure you have has much time to prepare as is necessary.

    I think the key part is to come in with a good understanding of Facebook's line of products in terms of metrics, features, audience.

    Interview Questions

    • Building a histogram of post reply count in SQL (number of posts with x replies, x+1 replies, etc).
      Building a table with a summary of feature usage per user every day (keep track of the last action by user and roll that up every day).
      Basic conditional probabilities (check out brilliant.org for their source of inspiration)  
      Answer Question

  9.  

    Data Scientist Interview

    Anonymous Interview Candidate
    No Offer
    Positive Experience
    Average Interview

    Application

    I applied through an employee referral. I interviewed at Facebook.

    Interview

    Inside referral and online application. Few emails with the recruiter to answer questions related to why I want to join FB and other logistical stuff. A phone screen, then onsite interviews

    Interview Questions

    • the phone interview had 2 parts, one was SQL based (I had the option to choose another language), and the other part was about using data to analyze missing/wrong information   2 Answers

  10.  

    Data Scientist Interview

    Anonymous Interview Candidate in Ann Arbor, MI
    No Offer
    Positive Experience
    Average Interview

    Application

    I applied through a recruiter. The process took a week. I interviewed at Facebook (Ann Arbor, MI) in February 2017.

    Interview

    Enjoyed the whole process of the recruitment. Impressed by the recruiter's attention to detail and the quick interview process. Facebook was proficient in getting all the required materials. No curve ball pretty straight forward interview questions.

    Interview Questions

    • What experiment would you run to implement new features on Facebook?   3 Answers

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