Interviewing process is constant optimization just like every other workflow process in a company. Disclaimer: I run interviewstreet.com which helps companies

Interviewing process is constant optimization just like every other workflow process in a company. Disclaimer: I run interviewstreet.com which helps companies screen & hire programmers using coding challenges. We have had a substantially HUGE number of developers screened (might not be able to reveal the exact number) through the process and using the data points, here's what we found (btw, this is also constantly optimized) a. Asking a 5-year experienced engineer to solve a graph theory challenge or a complex tree problem is a pretty useless indicator. The goal of such an interview challenge should be to test the problem solving skill of a candidate which is essential across any programmer role. Can this person actually take an array of objects, perform an operation to get the result such that it works for any size of the array without throwing an exception? The data structures used in the question should be simple enough to start working on the challenge. You will be surprised how many errors, corner cases come up which are often missed. And as you gradually increase constraints, you can check their thought process of how their algorithm changes. b. Make the problems interesting - put in actual effort to make the problems interesting, sometimes relevant to the problem you are actually solving. I often send this link to our customers(www.itasoftware.com/careers/puzzle_archive.html) and also help them design problems like this. That's by far the most interesting publicly available challenges. The other one is Quora, quora.com/challenges which is slightly harder though but very interesting (and has proved very effective!) c. Calibration: Surely github/bitbucket/SO profiles are important and can serve as a data point. However, it's probably going to be very hard to calibrate. A web server coded in Python vs a new MVC framework written in PHP - who is a better candidate? Who has actually thought through the design of the problem better? It's tough to evaluate. The programming challenge interviews act as a data point (one of the interview rounds) to check these skills in a contained problem/environment helping the company calibrate the performance against the rest of them. The problems should involve a combination of the ability to write good code, focus on problem solving skills and not on remembering an algorithm from the CLRS text book, intelligent thinking (not to be confused with weird math/geometry problems unless your company is working on that domain) and importantly the ability to catch hints and solve it in a better way. This is a data point, an essential one but there are more to technical interviews. If used in the right way, it can prove to be hugely effective for your process not only in streamlining but also as a way of generating interest from potentially interested programmers.