Whether you're creating new tests for each role or revising them every quarter, how you create your tests can have a big impact on your candidate's experience and results.
We analyzed over 16,000 tests to see what composition rules lead to the best candidate experience and the least negatively impacted score. What we found really interested us. Here are our top tips for creating a great test:
- Use 2 - 4 tasks in your test. While having lots of tasks seems like it'd give you better insights into your candidate, in most circumstances, including more than 3 tasks starts to have a negative impact on the candidate's performance due to time and focus. We design tasks to give you enough insights into the specific skill for you to make a decision on whether to take the candidate to the next stage of your process.
- Don't use really, really hard tasks. Under the hood, our difficulty-ranking system for tasks is a little more complex than 4 levels of difficulty. Within our Hard tasks level, we've included a couple of tasks that have intimidatingly low success rates. While there is a time to use these, most tests should stick to easy or medium-level tasks as including hard tasks has a negative impact on the candidate's confidence, experience, and therefore results. Always test drive a task before selecting it, and refer to the average scores per recommended time to see what you might expect from your candidates.
- Include a warm-up task to begin with. Entering a timed screening space can be intimidating, so beginning your test with an elementary task is a great way to get your candidate accustomed to the Codility IDE, and also in a problem-solving mindset.
- Don't use Training tasks. If you're recruiting, avoid including training tasks in your tests as they are not plagiarism protected to the same level as other tasks. In most cases, each training task has a similar substitute in the recruiting suite.
To help you automatically abide by these suggestions, we've built a series of tips and alerts which pop up when you're creating a test. Some examples below:

If you'd like more advice or to troubleshoot an issue, chat to us using the left chat icon on the bottom right of the screen.