Numerous resources explain how software companies (Microsoft, Google, Facebook, etc.) conduct coding interviews. Even books have been written on this topic, full with examples of coding questions.
I understand that one can get an accurate picture of a candidate's technical skills with such interviews, and that's of course very important. But other factors, too, are crucial. For example:
How motivated will the candidate be?
How productive is the candidate?
How organized is the candidate? For example, does s/he maintain a clean revision control history, or does his/her revision control history look like spaghetti of branches and merges?
How good commit comments does s/he write?
How clean code does the candidate write? How easy to read is the code?
How do software companies test such essential aspects?