How to prepare for a Data Analysis interview

For Data Analysis, your key role is to review and organize data to identify key insights into a business's customers and ways the data can be used to solve problems. Due to modern salesforce and CRM tools, data as a business asset has been rising in prominence over the last decade and as a data analyst you have an extremely diverse range of industries where your skills are needed, such as business, finance, criminal justice, science, medicine, and government.

Data analysts typically work with structured data to solve tangible business problems using tools like SQL, R or Python programming languages, data visualization software, and statistical analysis.

Common tasks for a data analyst include identifying informational needs, collecting and analyzing data through primary and secondary sources, cleaning and reorganizing data, performing trend analyses and translating these insights into actionable decisions. 

Types of data analysis

Descriptive analysis:
A descriptive analysis gives insight into events that have happened by summarizing quantitative data and presenting statistics. E.g. showing the distribution of sales across a department, or average sales figures per sales manager. 

Diagnostic analysis:
A diagnostic analysis gives insight into why events have happened by analyzing data and presenting insights and predicted causes. E.g. an influx of medical equipment sales due to the discovery of a new virus.

Predictive analysis:
A predictive analysis uses past data to examine and make predictions and projections about the future. E.g. Air Conditioning unit sales can be expected to increase approaching the summer months. 

Prescriptive analysis
A Prescriptive analysis takes all the insights gathered from the first three types of analysis and uses them to form recommendations for how a company should act. Using our previous example, this type of analysis might suggest a market plan to build on the success of the high sales months and harness new growth opportunities in the slower months. 

In our Wizco Blog, we covered the steps to prepare for a technical interview, which include requirements that the applicant be a problem solver and learn how to create real-time solutions during the interview and the role itself.

Interview preparation questions

Here are a few data analytics interview preparation questions to practice:

  1. How would you reverse a string in python?
  2. How would you populate a given excel file with VLOOKUP?
  3. What is the difference between SQL and MySQL?
  4. What are the different subsets of SQL?
  5. What are joins in SQL?
  6. What is the difference between CHAR and VARCHAR2 datatype in SQL?
  7. What is the primary key?
  8. What are Constraints?
  9. What does “Data Cleansing” mean? What are the best ways to practice this?
  10. Name the best tools used for data analysis.
  11. What is the difference between data profiling and data mining?
  12. What is the KNN imputation method?
  13. What should a data analyst do with missing or suspected data?
  14. Name the different data validation methods used by data analysts.
  15. Define Outlier
  16. What is “Clustering?” Name the properties of clustering algorithms.
  17. What is a K-mean Algorithm?
  18. Define “Collaborative Filtering”.
  19. Name the statistical methods that are highly beneficial for data analysts?
  20. What is an N-gram?
  21. What is a hash table collision? How can it be prevented?
  22. Define “Time Series Analysis”.


* Tips on answering these questions: align your experience to the attributes listed on the job posting and/or company culture and values

Questions to ask your interviewers:

The type of questions you may want to ask will depend on who is interviewing you, or which round of interviews you are currently in.

  1. What is your favorite thing about being a data analyst at this firm?
  2. What can I expect in terms of company culture? 
  3. What are some of the unexpected realities of being a data analyst ? 
  4. What common characteristics have helped people at this level quickly succeed and reach an outstanding performance? 
  5. I know data analytics to be very dynamic. What can I expect my day-to-day to look like ?

Interview follow up:

They say small kindnesses never go unnoticed and this is particularly true when it comes to interviewing.

A simple thank you email to your interviewer goes a long way to cementing you in their minds long after your interview is over. Your email could be as simple as thanking the interviewer for their time, or mentioning a particular part of the interview you enjoyed. This would also be a good opportunity to extend your interest in connecting via Linkedin. 

Your interviewer will generally set the expectation for when you can expect to hear back from them. If nothing is set, a good timeframe for a follow up is two weeks after the interview.

Checklist for the day of your interview: 

  1. Get a good night’s sleep - This allows your body and mind to recharge, leaving you refreshed and alert when you wake up, ready to ace your interview!
  2. Start your day with breakfast - You might find you feel a bit sluggish and struggle to focus if you don’t.  Breakfast positively affects your mental performance, including your attention, ability to concentrate and memory. Skipping the most important meal of the day can make some tasks feel harder than they normally would.
  3. Wear clothing you’re comfortable in - The dress code for data analytics positions can vary quite drastically from business professional to business casual, or even completely casual. With this in mind, it’s always better to overdress, rather than underdress. Comfortable clothing will also help you feel confident during your interview.
  4. Leave your house early - Proper planning will help you arrive on time for the interview and eliminate any last minute stress.  Double-check the interview location and your best route to get there. If you’re driving there yourself, it’s a good idea to consider where you might park. 
  5. If you are having an online interview, remember to log on early and test your setup. You should check your connection, camera and microphone, as well as ensuring your background or environment is free from clutter and distractions.
  6. Follow in Superman’s footsteps - Try this right before you go into the room or join your call. Stand with your feet shoulder width apart, place your hands on your hips and breathe deeply. This is the Superman pose, specifically developed to encourage your body to regulate breathing and allow your mind to clear and your nerves to calm. Plus, you’ll feel like you could leap tall buildings in a single bound - what better way to take your next steps to professional success?


Now that you’ve just taken your next steps towards succeeding in your career, be sure to take a look at the Wizco Blog for more insider tips and tricks and walk into every growth opportunity prepared.