The interview process for undergraduates is fairly standard compared to other consulting firms. There are two rounds of interviews. The first round consists of a behavioural interview and a case study type of interview, related to the type of work that ZS Associates is most famous for. The second round is a half day interview, with some time given to review a case and prepare some answers where you are quizzed on the details, an interview with a more senior Operations Research Associate to take you through some of the work they actually do, and interviews with managers and partners.

First I had a phone call with a current Operations team member. These were case style questions. I thought they were pretty easy, but apparently I had a few mistakes in my answers (that was the feedback I received from the recruiter after some pressing). One of the questions was something like: "Suppose we want to assign salesmen for our drug to various regions around the country. How will we go about this to maximize profit?" We were given something like 200 salesmen to assign to one of 300 or so different regions. We have a list of how profitable a salesman will be in each region, so clearly we just assign the salesmen to the top 200 most profitable regions on the list. Now suppose we can assign up to 2 salesmen to each region, and that the first salesman will always be more profitable than the second in any given region-- well, we simply update our list to contain entries indicating the profit that the second salesman will receive in each region, when 2 salesmen are present, and we again pick the top entries of our list. Then there was another similar question: "Suppose we have two drugs A and B. How will we market them?" The interviewer went into some detail about what drugs A and B will cure, and what sort of patients are eligible for them. Then you have to come up with some marketing ideas. A follow up question was "How will you assign sales reps to different regions in order to maximize profit? You have 200 reps, 300 territories, and each rep can sell either drug A or drug B" I gave an answer having to do with assigning reps to the regions where the marginal profit of an additional rep selling a specific drug (A or B) was highest. "How will we find such data on marginal profit?" Maybe we can compare sales of other similar drugs, or compare territories with similar demographics. We can have a few "test" regions and extrapolate from data gathered there. A week or so later, I had another phone interview, this time it was a behavioral interview. Asked "tell me about yourself" sort of questions, like "Tell me about a time you worked in a team/group to accomplish something" or "Tell me about a time you had to meet a deadline and you were worried you would not finish." "Why do you want to work for ZS Associates." Since I had apparently made some mistakes in my case interview, they wanted really good answers from me in this behavioral interview, I later learned from my recruiter. My answers apparently weren't up to snuff, so I was rejected :(