Metrics for programmer self evaluation

I'm programming from home and I want to know whether I'm more or less productive programming at 10 AM than I am when I'm programming at 8PM.

What metrics should I use to determine an answer to the question?

Ignoring the debate in the question's comments, a bunch of arbitrary productivity-ish metrics you could measure...

• lines of code written
• user stories/tasks completed
• bugs fixed
• tests written
• tests passing first time
• bugs found
• code churn vs new code (i.e. "right first time" vs "rewritten repeatedly")
• %age of time in IDE vs debugging
• %age of time in IDE vs non-work applications
• code quality (using another similarly arbitrary measure like FxCop compliance or cyclic complexity)
• code performance (against some arbitrary or customer-specified benchmark)

The best metrics tend to be combinations - say, "average of bugs found per line of code written" - rather than a single measure. Still, these are all subjective and innacurate.

I'd suggest the best thing to do is decide what your goal is when you're programming. Is it to produce high-quality code, or super-performant realtime code, or mission-critical-must-be-bug-free code, or do you just need to ship something that works in the shortest time? Until you've defined "productive", it's hard to suggest what would be a meaningful measurement.

I don't know if there is some established method for measuring productivity in programmers but assuming alertness and focus has a direct impact on productivity, I suppose you could set yourself some kind of mental arithmetic test with randomised questions and answers and take it at regular intervals.

It's a tricky one because you can't measure by lines, or problems solved (because they vary in scale and difficulty.) In fact, this article suggests that when attempting to measure programmer productivity, there is almost no correllation between the time it takes to complete a task and the quality of the finished product.