I really like this no-nonsense summary:
1. Think hard about what the students’ responses tell you about their knowledge
2. Split your findings into two piles: “things I care about” and “things I don’t care about”
3. For things you don’t care about, either forget them or change the test for next time
4. For things you do care about, split into two piles: “for reteaching” and “for building in”
5. Reteach and build in!