  To improve software developers' productivity has been the holy grail of
software engineering research. But before we can claim to have improved it, we
must first be able to measure productivity. This is far from trivial. In fact,
two separate research lines on software engineers' productivity have co-existed
almost in complete isolation for a long time: automated product and process
measures on the one hand and self-reported or perceived productivity on the
other hand. In this article, we bridge the gap between the two with an
empirical study of 81 software developers at Microsoft.
