# 2026-03-26

## Evening Briefing (8:15 PM ET)
Generated and posted to dashboard. Cron job `a954399d-6f5c-4811-9b0f-dc2a4b83833e`.

**Markets:**
- S&P 500: 6,477.10 (−1.74% / −114.80) — $900B-$1T equity value erased
- Nasdaq: −2.3% (tech-led selloff)
- Dow: −1.4%
- NVDA: −10%+, META: −7.92% (jury ordered $375M for harm to minors, Reality Labs layoffs)

**AI/Tech:**
- Claude Code v2 released — PowerShell tool (Windows preview), hooks, env vars
- Alex Finn: "AI killed dumb software, not all software" — niche problem-solving remains valuable

**Trump/Iran:**
- Reports: Trump weighing ground operation on Iran's Kharg Island oil hub
- Trump claims Iran allowed 8-10 tankers through Hormuz as goodwill gesture

**Posted to dashboard:**
- Briefing: id 23a12629
- News items: market selloff, Claude Code v2, Trump/Iran, Alex Finn insight, Clarivate AI50

**Discord DM sent** to johanjongsma with dashboard link.

---

## Rozemarijn (Roos) Study Session — Lecture 7 + Lecture 8

**Session:** All-day study session, ~10:20 AM – 5:38 PM ET
**User:** Rozemarijn (Discord ID: 1486461895136252115, username: rozemarijn)
**Exam:** Real Estate Research, Thu April 2, 2026, 2 hours, Univ. of Groningen

### Lecture 7 — COMPLETED ✅
All slides covered. Key topics:
- Functional form (linear, log-linear, log-log) and interpretation of coefficients
- Polynomials (concave/convex functions, x²)
- Endogeneity — omitted variable bias, dirty x
- Durbin-Wu-Hausman test (test for endogeneity)
- IV / 2SLS: instrument validity (relevance + exogeneity), two-stage procedure
- Weak instrument test: F-statistic > 10 rule of thumb
- Interaction variables (city-specific slopes)
- Transformations summary table (linear/log-linear/log-log)

**Roos' weak areas noted:**
- Needed multiple explanations of predicted value x̂ (eventually understood with numeric example + analogy)
- λ notation confused her (explained it's just Stage 1 β)
- Prefers: consistent notation, always show formulas, explain in steps
- Can switch to Dutch when struggling

### Lecture 8 — IN PROGRESS (slide 17 of 24)
Topics covered so far:
- TRUE model (y = x₁β₁ + x₂β₂ + ε)
- Restricted vs Unrestricted model (pooled vs separate group lines)
- Number of parameter restrictions: DF1 = (g-1)×k, DF2 = n - g×k
- Chow test — full calculation with wage differentials example (F=1.30, reject H₀)
- What to report after Chow test (RSS + k always, pooled vs separate based on result)
- CLRM assumptions A1–A5 (Roos knows A4 well; A1/A2/A3/A5 need drilling)
- Consistency vs Efficiency (A4 violation = biased = worst; A2/A3 = inefficient SE)
- Slide 17: 4 tests overview (F-test, Chow test, White's test, RESET/functional form test)

**Still to cover in lecture 8:**
- Slide 18: F-test statistic formula (has diagram)
- Slides 19-20: White's test for heteroskedasticity (detail)
- Slide 21: Cross-sectional data analysis workflow
- Slides 22-24: Formative test exercises (Exercise 1 + Exercise 2)

### Roos' Notation Preferences (STRICT — always follow)
From her green table image:
1. E(μₜ) = 0
2. var(μₜ) = σ² < ∞
3. cov(μᵢ, μⱼ) = 0
4. cov(μₜ, xₜ) = 0
5. μₜ ~ N(0, σ²)
Always use μ (not ε or u) for error term when tutoring Roos.
Always consistent notation — no variation between explanations.

### Mirror To-Do List Created
Full study plan written out per day (March 26 – April 2).
Roos has Paradiso performance Fri evening + concert Sat evening (social commitments noted in study plan).

### CLRM Drilling Needed
Roos explicitly flagged she needs to know A1–A5 by heart.
- ✅ A4 — understood well
- ⏳ A1, A2, A3, A5 — come back to drill these before exam