Session Notes — Econ 326

2026-02-15

File changes:

• Created /Users/vmarmer/Documents/teaching/Econ 326/326_ps_05.tex — Assignment 5 (2 pages)
• Updated /Users/vmarmer/Documents/teaching/Econ 326/TODO.md — all items marked completed

New content (326_ps_05.tex):

• Q1: Intercept-only model Y_i = beta_0 + U_i — interpret beta_0, derive E[sum hat_U_i^2] = (n-1)sigma^2, propose unbiased estimator of sigma^2

• Q2: Derive Var(beta_1_WLS

  X) under classical assumptions for simple regression with arbitrary positive weights w_i(X_i); includes hint showing WLS estimator formula with weighted means

• Q3: R output (rent ~ income, n=26) with missing entries A-D (SE, CI bounds); interpret 95% CI; construct 90% CI and compare widths
• Q4: Propose one-sided CI (-inf, U] for beta_1 using t critical values; prove coverage = 1-alpha under normality

Config changes:

• Added “Session notes” and “TODO list” sections to project CLAUDE.md (chezmoi source)
• Added user preferences (session notes, TODO tracking) to project MEMORY.md