6 ms·

What kinds of technical questions do they ask in a data science interview?

minimaxir 9y ago
On the stats side, often higher-level theory questions, such as "How does the k-means algorithm work?", "How do you select the best k for k-means?", "What is the curse of dimensionality?" which again would not be things covered at a data boot camp or data science thought pieces on Medium. On the technical side, there is often more-advanced SQL (nested JOINs + PostgreSQL window functions). On the big data side, there is often discussion of distributed systems (e.g. Spark clusters) and practical algorithmic complexity at scale (i.e. instant fail if you suggest anything loglinear or slower).
- moab 9y ago
  I overheard some colleagues talking about a recent interview where a candidate with "stellar industry experience", i.e. Kaggle wins and previous ML experience at a valley company, who couldn't explain Bayes rule to them, let alone rederive Naive Bayes. While books like the one below are extremely theoretical, anyone interviewing for these kind of roles should spend at least a week or two just looking through this to see what kind of algorithms and properties are studied in theory. Foundations of Data Science (Blum, Hopcroft, Kannan) https://www.cs.cornell.edu/jeh/book2016June9.pdf https://www.cs.cornell.edu/jeh/book2016June9.pdf
  - reader5000 9y ago
    This is like not hiring a [big name coding competition] winner because he didn't know radix sort.
    - mmierz 9y ago
      I think it's more like not hiring a big name coding competition winner because they never bothered to learn how to use version control, or any coding best practice, or any language other than C. Trying to do data science with zero knowledge of the fundamentals of probability is dangerous. Bayes rule isn't some kind of deep magic, it's covered within the first few lectures of an undergraduate probability course and it's absolutely necessary to understand the output of any machine learning model.
      - reader5000 9y ago
        >I think it's more like not hiring a big name coding competition winner because they never bothered to learn how to use version control, or any coding best practice, or any language other than C. Depends on what you're hiring for, but I'll take "competition winner with no version control" over "average programmer with expert VC capabilities". >Bayes rule isn't some kind of deep magic Yes, it's largely conceptually obsolete. The people jamming out weekly SOTA machine learning models on arxiv aren't sitting around meditating on conditional probabilities. They're making little tweaks to giant models that are basically impossible for a human to comprehend.
        XiaomiFan 9y ago
        > Yes, it's largely conceptually obsolete. Wow
        mmierz 9y ago
        I'm not sure I agree with that. I don't know any ML researchers that don't know about probability, but maybe they exist somewhere. Machine learning research isn't a good model for "data science" writ large. Maybe there are some jobs and some problem spaces where you can just tweak big black box models and you don't ever need to think about what their output means. But if you're the kind of data scientist who helps make decisions with data -- you better believe statistics and probability is conceptually relevant. As soon as models meet the real world, you've got to understand probability in order to know what to expect.
        achompas 9y ago
        > Yes, it's largely conceptually obsolete. I'm sorry, what? How did you arrive at a point where you believe this is true? This is like calling compilers "obsolete." Is it because you believe deep learning has "taken over" or something?
        reader5000 9y ago
        Try to derive e.g. a face detector from bayes theorem. You immediately arrive at computationally intractable sums/integrals. Yet, we have super-human image classifiers. Therefore, bayes theorem is obsolete. Sure, you can try to retrofit bayes theorem on top of a neural net, but who cares?
- resolaibohp 9y ago
  The stat questions you mentioned are all answered from a introductory modeling book or class. I am surprised those subjects are not even talked about in a data boot camp.
- gipp 9y ago
  Having never been to a data boot-camp -- what _do_ they teach there, if those wouldn't be covered?
  - minimaxir 9y ago
    Galvanize, the one mentioned in the article and markets the most, is vague on their curriculum but is more scikit-learn oriented. https://www.galvanize.com/san-francisco/data-science#curriculum https://www.galvanize.com/san-francisco/data-science#curricu... Metis, another known bootcamp, does explicitly mention things like k-means, which is something I didn't know: https://www.thisismetis.com/data-science-bootcamps https://www.thisismetis.com/data-science-bootcamps
    - resolaibohp 9y ago
      Having spoken to several students as well as looking at their GitHub projects from the galvanize data science program, I am fairly confident they cover those stats subjects in question. Not to say that a data science boot camp is all you would ever need to know, but I would give them a little more credit in what they teach. That galvanize link is not really their syllabus, they probably keep it vague to force you to sign up to their email list to get the real one.
- blahblah3 9y ago
  All the stats stuff you mentioned (and more) is laid out very nicely in the second chapter of "Elements of Statistical Learning" https://web.stanford.edu/~hastie/Papers/ESLII.pdf https://web.stanford.edu/~hastie/Papers/ESLII.pdf
- raizinho 9y ago
  I'm not sure which bootcamps you're referring to, but I went to one that went into the topics from your first sentence in depth. The topics from your second sentence were not as thoroughly explored, though.

On the stats side, often higher-level theory questions, such as "How does the k-means algorithm work?", "How do you select the best k for k-means?", "What is the curse of dimensionality?" which again would not be things covered at a data boot camp or data science thought pieces on Medium. On the technical side, there is often more-advanced SQL (nested JOINs + PostgreSQL window functions). On the big data side, there is often discussion of distributed systems (e.g. Spark clusters) and practical algorithmic complexity at scale (i.e. instant fail if you suggest anything loglinear or slower).

moab 9y ago
I overheard some colleagues talking about a recent interview where a candidate with "stellar industry experience", i.e. Kaggle wins and previous ML experience at a valley company, who couldn't explain Bayes rule to them, let alone rederive Naive Bayes. While books like the one below are extremely theoretical, anyone interviewing for these kind of roles should spend at least a week or two just looking through this to see what kind of algorithms and properties are studied in theory. Foundations of Data Science (Blum, Hopcroft, Kannan) https://www.cs.cornell.edu/jeh/book2016June9.pdf https://www.cs.cornell.edu/jeh/book2016June9.pdf
- reader5000 9y ago
  This is like not hiring a [big name coding competition] winner because he didn't know radix sort.
  - mmierz 9y ago
    I think it's more like not hiring a big name coding competition winner because they never bothered to learn how to use version control, or any coding best practice, or any language other than C. Trying to do data science with zero knowledge of the fundamentals of probability is dangerous. Bayes rule isn't some kind of deep magic, it's covered within the first few lectures of an undergraduate probability course and it's absolutely necessary to understand the output of any machine learning model.
    - reader5000 9y ago
      >I think it's more like not hiring a big name coding competition winner because they never bothered to learn how to use version control, or any coding best practice, or any language other than C. Depends on what you're hiring for, but I'll take "competition winner with no version control" over "average programmer with expert VC capabilities". >Bayes rule isn't some kind of deep magic Yes, it's largely conceptually obsolete. The people jamming out weekly SOTA machine learning models on arxiv aren't sitting around meditating on conditional probabilities. They're making little tweaks to giant models that are basically impossible for a human to comprehend.
      - XiaomiFan 9y ago
        > Yes, it's largely conceptually obsolete. Wow
      - mmierz 9y ago
        I'm not sure I agree with that. I don't know any ML researchers that don't know about probability, but maybe they exist somewhere. Machine learning research isn't a good model for "data science" writ large. Maybe there are some jobs and some problem spaces where you can just tweak big black box models and you don't ever need to think about what their output means. But if you're the kind of data scientist who helps make decisions with data -- you better believe statistics and probability is conceptually relevant. As soon as models meet the real world, you've got to understand probability in order to know what to expect.
      - achompas 9y ago
        > Yes, it's largely conceptually obsolete. I'm sorry, what? How did you arrive at a point where you believe this is true? This is like calling compilers "obsolete." Is it because you believe deep learning has "taken over" or something?
        reader5000 9y ago
        Try to derive e.g. a face detector from bayes theorem. You immediately arrive at computationally intractable sums/integrals. Yet, we have super-human image classifiers. Therefore, bayes theorem is obsolete. Sure, you can try to retrofit bayes theorem on top of a neural net, but who cares?
resolaibohp 9y ago
The stat questions you mentioned are all answered from a introductory modeling book or class. I am surprised those subjects are not even talked about in a data boot camp.
gipp 9y ago
Having never been to a data boot-camp -- what _do_ they teach there, if those wouldn't be covered?
- minimaxir 9y ago
  Galvanize, the one mentioned in the article and markets the most, is vague on their curriculum but is more scikit-learn oriented. https://www.galvanize.com/san-francisco/data-science#curriculum https://www.galvanize.com/san-francisco/data-science#curricu... Metis, another known bootcamp, does explicitly mention things like k-means, which is something I didn't know: https://www.thisismetis.com/data-science-bootcamps https://www.thisismetis.com/data-science-bootcamps
  - resolaibohp 9y ago
    Having spoken to several students as well as looking at their GitHub projects from the galvanize data science program, I am fairly confident they cover those stats subjects in question. Not to say that a data science boot camp is all you would ever need to know, but I would give them a little more credit in what they teach. That galvanize link is not really their syllabus, they probably keep it vague to force you to sign up to their email list to get the real one.
blahblah3 9y ago
All the stats stuff you mentioned (and more) is laid out very nicely in the second chapter of "Elements of Statistical Learning" https://web.stanford.edu/~hastie/Papers/ESLII.pdf https://web.stanford.edu/~hastie/Papers/ESLII.pdf
raizinho 9y ago
I'm not sure which bootcamps you're referring to, but I went to one that went into the topics from your first sentence in depth. The topics from your second sentence were not as thoroughly explored, though.