<p>Alright, so in the textbook that our class is using (Stats: Model the World), for regression inference, it states that the degrees of freedom is n - 2. However, I just took an AP Statistics practice exam (the 2007 AP Exam in particular) and in the answer key it says that the degrees of freedom is n - 1. Can anyone confirm which one is right? I tried looking online and everywhere else says it's n - 2. Did CB just have a mistype?</p>
<p>df = n-1 if it is a t-distribution
df = n-2 if it is a regression inference</p>