Verified by Data Scientist at Cognizant

Cognizant Data Scientist Interview Guide

Interview Guide Feb 25

The role of a Cognizant Data Scientist

A data scientist is an expert in handling large amounts of structured and unstructured data. A data scientist combines computer science, mathematics, and statistics to analyze data. In addition to analyzing, processing, and modeling data, they interpret results to create actionable plans for businesses and organizations.

Cognizant is a company that offers business consulting, information technology services, and outsourcing. Cognizant also helps other companies modernize technology, reimagine processes, and transform their customer experiences so they can stay competitive in an ever-evolving world.

Role of a Data Scientist at Cognizant

  • Provide clients with access to data to help them make decisions.
  • Managing new research, collecting data, and analyzing business needs. 
  • Making the data more suitable for analysis by transferring it into a new format.
  • Collecting, analyzing, and reporting data with the BI team.
  • Finding useful information in large data sets.
  • Creating business presentations and reports. 

Preferred Skills/Qualifications

  • Should have at least 2+ years of experience.
  • Experience with programming languages like SQL, Python, R, and Scala
  • Experience with business intelligence tools (e.g., Tableau)
  • Strong mathematics skills (such as statistics and algebra) 
  • Analyzing data in an exploratory manner with an advanced level of proficiency
  • Knowledge of common data science toolkits
  • Knowing the statistics is a must.
  • Excellent technical writing skills.
  • A clear, concise way of communicating complex information.
  • An understanding of how to visualize data effectively for a given project or study.
  • Experience with machine learning and AI 
  • Familiarity with data management tools 
  • Analytical, and problem-solving capabilities
  • Ability to work alone as well as with people from various backgrounds in a team.
  • Paying close attention to the smallest of details

Cognizant Data Scientist Interview Guide

The interview process in a nutshell:

The interview process for the Cognizant data scientist role consists of 3 stages:

  • Online Quiz Round
  • Live Technical Interview
  • Behavioral Interview

Online Quiz Round


In this round, you will be tested on the basic concepts of SQL, Python, and Java. Typically, there will be four coding questions along with two SQL queries.

Interview Questions

  • Difference between a list and a tuple in Python
  • Find missing elements in a list in Python.
  • How to concatenate two tuples?
  • How can you initialize a 5 x 5 NumPy array with only zeroes?
  • What functions are used in Python?
  • SQL query to implement inner join.
  • What will be the output of the following code?

import java.util.Arrays;

import java.util.Comparator;

public class comparator test

public static void main(String args[])


String[] ar= {“c”,”d”,”b”,”a”,”e”};

InnerClass in = new InnerClass();

Arrays.parallelSort (ar, in);

for (string str : ar)

System.out.println (str + ””);

System.out.println (Arrays.binarySearch (ar, “b”));


Static class InnerClass implements ComparatorString>


public int compare (String s1, String s2)


return s2.compareTo(s1);




  • What will be the output of the following code?

import java.util. LinkedHashSet;

import java.util.Set;

public class LinkedHashSetTest {

main (static void main) (String args [])


Set s = new LinkedHashSet();

s.add (“1”);

s.add (1);

s.add (3);

s.add (2);

System.out.println (s);



Technical Interview Round


The interviewer will ask you to introduce yourself at the beginning of the interview. Prepare your introduction in advance and make sure what you say reflects your confidence. In most cases, the introduction determines the tone and direction of the interview.

What the interviewer will assess

  • Knowledge of the core aspects of your field
  • Coding skills
  • Programming efficiency in multiple languages


  • If Python is what you have stated is your preferred language, do a thorough review of data structures in Python.
  • Have an explanation been drafted that discusses your objective, the challenges you faced, how you overcame them, or any limitations you faced.
  • Have a good understanding of the built-in functions in SQL. Whenever you are writing your code, be aware of what you are saying. Explain the steps you are taking as you go. Also, make it engaging for your interviewer.

Interview Questions

  • Build a data frame using lists.
  • What are the most important features of Python?
  • What are pandas?
  • Why is Python so widely used?
  • C and C++ have pointers. How does a pointer translate in Python?
  • What is a confusion matrix?
  • What are the different parameters in the Xgboost Algorithm?
  • What is a binary heap?
  • What is a balanced tree and why is that important?

Practice more such questions with a Cognizant Data Scientist

Book Now!

Behavioral Interview


In the behavioral interview round, candidates are generally asked to share examples of specific situations they’ve been in where they had to use certain skill sets. This is an excellent opportunity for you to demonstrate what you are capable of doing for this company in the future.

Interview Questions

  • Describe a time when you worked with someone who had a different personality than your own.
  • How did you handle a conflict while working on a team?
  • How did you make a client feel satisfied with your service?
  • Tell me about a time when you had to deal with a lot of pressure. What was going on and what did you do?

Nail your data scientist interview at Cognizant with one of our experts

Book Now!