There are many different ways of assessing technical skills, each has their own benefits and drawbacks. When deciding on which type of interview format to use, consider:

Technical Questions

This kind of interview is similar to normal 1-1 or panel style interview. Ask questions that will test a candidate’s knowledge of technical concepts.

👍 Pros: A good way to understand how well someone can explain technical concepts in broad terms and to different audiences.

👎 Cons: May disfavor people who have good technical abilities, but low presentation and public speaing skills.

Live Coding

In a live coding interview, the candidate solves programming problems in front of the interviewer. This is commonly done in a coding interview platform (e.g. CoderPad), an IDE of the candidate’s choice, or on a whiteboard.

👍 Pros: Less time intensive for the candidate.

👎 Cons: Does not represent the normal development environment and may cause the candidate stress and performance anxiety.

Take Home Exercises

Take home exercises allow the candidate to demonstrate their skills on their own time. Often a problem or dataset is given to the candidate, and then they are asked to demonstrate a solution or answer questions in a notebook (e.g. Jupyter or R Markdown notebook). Be sure to limit the number of (un-paid) hours that a candidate is expected to spend on a take home exercise (e.g. 2 hours max), otherwise this type of assignment can become exploitative. It should be an open-ended assignment (an analysis or a task) with plenty of room for improvisation.

👍 Pros: No performance anxiety, can evaluate candidates consistently on the same questions/tasks.

👎 Cons: Difficult to limit the time a candidate can spend on an assignment, and has the potential to become exploitative and time-consuming.

Code Review

In a code review-style interview, the interviewer and candidate sit down together to go over an existing piece of code. The interviewer can ask the candidate to demonstrate a review of the code, or may ask more structured set of questions about the code. This kind of interview can also include the results of code (e.g. data visualizations/figures, statistical results, applications).

👍 Pros: Assesses communication skills and ability to explain concepts. Provides insight into how a candidate would react in a team environment and code reviews.

👎 Cons: Could cause performance anxiety and stress. Does not evaluate code that the candidate has written.

Code Samples

Have candidates point to a technical project on GitHub that they’ve already done and are proud of. If a candidate doesn’t have something available on GitHub, they may still be able to share something like a Quarto document or Jupyter notebook with you. What language do they like? How do they structure code? Do they comment code and follow other good practices? What is their commit cadence like?

👍 Pros: Does not require unpaid hours of work for the candidates, shows real work and contributions, could encourage a more diverse set of applicants to apply (i.e., more applicants who would not be able to spend hours of unpaid work on take home exercises).

👎 Cons: May disfavor candidates who work with protected/proprietary code, or candidates who are underrepresented in open source software communities.

Other Ways of Evaluating Technical Skills

In addition to a technical interview, look for: