PP240B Section Topic Suggestions by Ji-Won Choi

Bias in observational studies

jiwonchoi6 — 2025-01-24 01:31:34 UTC

what's the difference between selection bias and omitted variable bias?

variance

jiwonchoi6 — 2025-01-24 18:17:29 UTC

what does variance mean?

Struggling with R

rachel_heimann — 2025-01-30 18:01:41 UTC

I feel like he's speaking another language in class and have no idea what's happening in R, and I have class during the R office hours. What resources should I use?

Fitted Residuals Regression Estimator of b (PS#2 Problem 4)

2025-02-25 18:52:34 UTC

I don't understand this. I get how the b estimator is cov(x,y)/var(x) for a normal bivariate regression, but why is it different in this case?

Applying formulas

rachel_heimann — 2025-02-25 19:19:15 UTC

The thing I'm struggling most with is being able to recognize which formulas mean what (it seems like every definition can be written in 4 different ways). Can you help us think through how to organize our notes so that we can actually use them? (also, I know Steve will be providing the cheat sheet-can you ask him to give it to us ahead of the test so we can use it to study with?)

Increased Understanding of Reduced Form Equations

2025-04-08 17:23:40 UTC

I still really don't get the reduced form equation stuff but he mentioned it again this week so it feels like we need to know it? Is it that we need to mathematically decompose the system of equations to understand what it looks like on a case-by-case basis? The problem set problem had more variables than the class one and I was just kind of lost.