Actually we've tried giving them a choice. Most chose to do the assignment rather have to go through a high pressure interview answering whiteboard questions. W

Actually we've tried giving them a choice. Most chose to do the assignment rather have to go through a high pressure interview answering whiteboard questions. We're not asking them to solve problems that could possibly be used in any of our products so they don't feel taken advantage of and it's usually something fairly simple (e.g. design a parking lot management system). All in all they probably spend as much time writing the small sample app as they would in the typical all-day interview loop.