Data Science Consulting Interview Questions

40,373 data science consulting interview questions shared by candidates

Q1. Given n float numbers {x1, .... xn} which are drawn from some truncated normal distribution where all numbers greater than 10 are discarded (and hence all these numbers are <= 10). How do you estimate the mean/sd of the distribution from which these numbers are drawn? Q2. Suppose we have all Walmart transactions stored in the format (timestamp, item ID, amount). How do you choose a data structure to store the data so that given any time window (start, end), we can easily query the total amount inside this window? Q3. Some SQL questions, i.e. given some schema, write SQL to query some desired data. Q4. Describe some variables that might be useful to tell whether an online transaction is risky.
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Data Scientist

Interviewed at Walmart

3.4
Nov 30, 2017

Q1. Given n float numbers {x1, .... xn} which are drawn from some truncated normal distribution where all numbers greater than 10 are discarded (and hence all these numbers are <= 10). How do you estimate the mean/sd of the distribution from which these numbers are drawn? Q2. Suppose we have all Walmart transactions stored in the format (timestamp, item ID, amount). How do you choose a data structure to store the data so that given any time window (start, end), we can easily query the total amount inside this window? Q3. Some SQL questions, i.e. given some schema, write SQL to query some desired data. Q4. Describe some variables that might be useful to tell whether an online transaction is risky.

The Interviewer has a list of problems mentioned below. I was asked to pick one of them and code the algorithm 1. There are few points generated which belong to two classes. I was asked to code the logistic regression without using any external library like scikit-learn or scipy. I was to asked to code entirely in numpy 2. There's a question on solving PCA using iterative methods 3. There's a question on solving eigen vectors using iterative methods 4. There's a question on clustering using k-means on a psuedo generated clusters. 5. One more Question is to implement EM algorithm using numpy. During the process of interview and coding lot's of questions related to optimized numpy code. Ex he asked do you what broadcasting is ?. Mostly he tried to make me do vectorized numpy coding
avatar

Staff Data Scientist

Interviewed at Walmart

3.4
May 29, 2020

The Interviewer has a list of problems mentioned below. I was asked to pick one of them and code the algorithm 1. There are few points generated which belong to two classes. I was asked to code the logistic regression without using any external library like scikit-learn or scipy. I was to asked to code entirely in numpy 2. There's a question on solving PCA using iterative methods 3. There's a question on solving eigen vectors using iterative methods 4. There's a question on clustering using k-means on a psuedo generated clusters. 5. One more Question is to implement EM algorithm using numpy. During the process of interview and coding lot's of questions related to optimized numpy code. Ex he asked do you what broadcasting is ?. Mostly he tried to make me do vectorized numpy coding

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