So a couple people asked for this so I thought I'd summarize the process of how reviews in general work here at MS, plus some specifics about how we handle software developers.
First off, evaluating software engineers relative to each other is a bit tough to do purely objectively. Most of this is our own doing, because of the way software development has often been done over the last 20 years. Deriving metrics for large, complex projects can be difficult. You'd like to say "well,...