6 · Models and uncertainty
Wednesday, September 30, 2026
This page is a stub. Materials appear here before the meeting.
What you should be able to do after this meeting. Read a coefficient in the units of the problem. Say what a p-value does and does not tell you. Tell an explanatory question apart from a predictive one.
Handouts
Where to read more
Adams ch. 11 on descriptive statistics and ch. 12 on correlation and regression.
Session A · 2:05–3:15
Linear regression, non-linear models, count models. Described, not derived. What each estimates, and how to read a coefficient in the units of the problem. Then uncertainty. Residuals and errors, sampling variation, what a standard error actually states, and where p-values come from. More usefully: what they are not. Finally the distinction that decides half the projects in this room. Explaining is not predicting. A model can predict well and still tell you nothing about what to do.
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.
Ten minutes of simulation first, driven from the front. Draw from a world you control. Watch the p-value distribution under the null. Move the sample size and the variation, and watch it shift. Then fit the same world in and out of sample, and watch an excellent-looking model fail on data it has not seen. Nothing to install. Then the cards. Each team gets an analyst who ran something and said something about it, and every one overclaims differently. A count outcome fitted by OLS and predicted below zero. A 0.03% lift called highly significant across two million users. A wide interval called no effect. An elasticity estimated off two price changes in three years. A churn probability of 112%. Work out what they are actually entitled to claim. Then a team is drawn at random to defend that while the room pushes back. The last line on the sheet is the one that matters: is your own project at risk of the same error?
Your team’s output is submitted before you leave.
Due
Rate your teammates