Often, when I hear questions about how to measure something, I am compelled to respond with a question? And 9 times out of 10, that question is "For what purpose?" What do you want to do that you think you need to know about "efficiency" of programmers? Saving Changes...
Here is an easy way: Ask you programmers to give you a time estimate and a deadline for a task.If they finish in time and in buget you got the right crew. Saving Changes...