When developing interview questions to assess a candidate’s computer programming skills, you should focus on a few key areas: the understanding of programming concepts, the ability to write clean and efficient code, the knowledge of specific languages or tools relevant to the position, and the capacity to solve problems and debug code.

Understanding of Programming Concepts

Regardless of the specific language, programmers should have a strong understanding of fundamental programming concepts. These include variables and data types, control structures (like loops and conditionals), functions, error handling, and data structures (like arrays, vectors, and data frames). Consider asking questions that probe the candidate’s understanding of these concepts, perhaps by asking them to explain a concept in their own words or to write a simple piece of code that demonstrates their understanding. Understand when you are assessing the thought process versus the minutae of a programming language - let candidates know they can use human-readable pseudocode.

Writing Clean and Efficient Code

Being able to write clean, readable code is a crucial skill for any programmer. You might ask the candidate to review a piece of code and suggest improvements, or to explain how they would approach writing code for a given task.

Knowledge of Specific Languages or Tools

The languages or tools a programmer needs to know will depend on the role. Common languages include Python, R, SQL, or JavaScript, and tools might include Git, Docker, or specific frameworks or libraries. Make sure to ask questions that assess the candidate’s proficiency in the languages or tools they’ll be using in the role. This could involve asking them to write a piece of code in a specific language, to explain how they would use a tool to accomplish a task, to discuss the pros and cons of a language or tool, or to have them explain code they have previously written.

Problem-Solving and Debugging

Problem-solving is at the heart of programming. Consider asking questions that test the candidate’s problem-solving skills, such as asking them how they would debug a piece of code that isn’t working as expected. The goal is to understand their thought process and approach to problem-solving. Asking open-ended questions and encouraging the candidate to talk through their thought process can provide valuable insights into their problem-solving abilities and how they approach their work. You could also consider telling the candidate, “it is okay if you don’t know, but tell me how you would figure it out.”