9 · Research designs II

Wednesday, October 21, 2026

This page is a stub. Materials appear here before the meeting.

Date not final. Instructor traveling — moves to Oct 20 or Oct 22; date to be confirmed.

What you should be able to do after this meeting. Draw your project’s design as a graph. Name the single assumption carrying the estimate — the one you would have to defend to a sceptic.

Where to read more

Remix ch. 8 and 9 on panel designs and difference-in-differences, ch. 10 if your rollout is staggered. Mostly Harmless ch. 5.

Session A · 2:05–3:15

The same discipline on harder designs, each drawn first. Difference-in-differences: the confounders you cannot measure are the ones that do not move. Parallel trends is what that assumption looks like drawn. Panel data with local fixed effects: which arrows the fixed effects erase, and which survive untouched. Event studies: the same picture with time on it. For each, what identifying variation is left once the fixed effects are in, and what assumption is carrying the estimate.

Session B · 3:30–4:30

Every session B opens with a ten-minute team check-in: what you did since last week, what is stuck, and who is doing what next. Written down, and handed in with that session’s work.

Same format, higher stakes. First a card apiece — a staggered rollout, a state border, a fee that changed for accounts opened after a date. Fifteen minutes to draw it and name the design. Then the part that counts. Teams are drawn at random to put up their own project’s design, draw the graph, state the assumption carrying the estimate, and defend it while the room tries to break it. Everyone presents eventually. Nobody knows when. Whatever survives is the figure that goes in your identification section, so draw it to keep. And write down the attack that landed. That is your limitations paragraph.

Your team’s output is submitted before you leave.

Due

Project pitch — one page, presented in class