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Technical Phone Screens

A technical phone screen is an early conversation between a candidate and a current employee of a hiring company with technical ability. Most commonly, technical phone screens are conducted by engineers at the hiring company, but they may also be conducted by others, such as recruiters with deep technical knowledge. The content of a technical phone screen can range from a simple conversation to live coding.

​confusion​ Note that for some candidates—particularly high-value candidates, referrals, and outbound candidates—interviewers may begin with a more general first conversation to get to know the candidate and gauge their interest. Depending on their experience, these candidates may skip technical phone screens altogether.

​important​In general, technical phone screens are better for disqualifying obviously poor candidates than for qualifying them. Secondarily, they can help identify potential superstars whom interviewers will want to focus additional energy on courting.

It is easier and more important in a short, abbreviated phone screen to figure out that a candidate doesn’t understand something like recursion and thus fails to qualify than to assess whether they have deep algorithmic ability, which is hard to measure quickly and reliably. Harder questions tend to make bad phone-screen questions because the phone format makes hard questions more difficult for candidates to succeed at, and because even strong candidates may miss any given interview question. Starting the process with harder questions also means you are exposing your question set to a larger pool of candidates, increasing the likelihood of leaks. Therefore, a phone screen process focused on sorting out bad fits will work better than one that tries to search only for stars.

​story​ “At Dropbox, we tried moving hard questions to the front on the theory that harder questions are a better filter and that we would save time downstream. Many fewer candidates made it through the initial screening process, reducing the number of onsites. Only the truly outstanding candidates made it through, and we filtered out a lot of the lower-skilled candidates. However, we also filtered out a large number of candidates who could have been good. On examination, we realized that if you gave a good candidate two hard questions, they would usually get at least one down well and struggle a bit on the other. These people would do well on a full interview panel, but if you happened to give them the wrong question in the the phone screen, you would reject them, which increased the rate of false negatives. We moved to a system where the phone screen is focused on filtering out obvious wrong fits while giving room for truly exceptional candidates to shine.” —Scott Woody, former Director of Engineering, Dropbox

​story​ “At Triplebyte, we get to see how the same candidate does at different companies. And it’s far more common than you might think for someone to be screened out top of funnel at one company and then go on to do really well at another company. This is fine, as long as the screening question that was used really is in an area that the company cares about. There is far more variance in candidate knowledge (even experienced, skilled candidate knowledge) than most hiring managers think. So, make sure if you ask a screening that requires knowledge of, say, time complexity, that you really do need people to understand that. Because there are productive, experienced, senior engineers who don’t understand complexity analysis. And if you don’t require web dev experience, make sure you don’t ask a question that requires someone to understand fullstack dev.” —Ammon Bartram, co-founder and CEO, Triplebyte

Skipping the Phone Screen

The phone screen is almost always necessary because online challenges, whether or not they are combined with resume screens, will not give you enough signal to move someone to an onsite. You can often skip the initial phone screens for candidates whose previous experiences make it clear that they would be minimally capable of performing in the onsite process (for example, that they possess baseline coding fluency and problem-solving skills). Having candidates share open-source work on GitHub can be a strong early sign of programming ability. Phone screens might also be skipped for people who are high-valued or are referrals. If the chance that someone would fail the phone screen is very low, and you have the resources to bring them onsite, it’s wise to do so. The more stages you include in the process, the more likely some number of candidates will drop out.

Removing a step is a simple way to accelerate the pipeline and should not compromise signal if the same material is covered in later stages.

Onsite vs. Remote

Typically, the large part of the interview process happens onsite, but this is changing as more companies build remote teams or wish to accommodate candidates who are not local. You can use many interview formats either in person or remotely; this includes even live coding challenges. A company’s resources and the candidate’s availability usually determine whether a particular part of the process will be conducted remotely or onsite.

Remote interviews have a few specific use cases:

  • Typically (but by no means universally), remote interviews are concentrated earlier in the funnel and may include:

    • Online challenges and take-homes.

    • Phone screens, both general and technical.

    • Technical screening questions, questions where the candidate can code in the browser during a screen share, and light behavioral questions. Note that while you may encounter binary decision points or spikes in the signal during remote interviews, this is not a useful format for making more fine-grained decisions.

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