Session 4 · Bias & effect: can we trust it, how big is it?
Week 4 · Saturday · online, 19:30–22:30 (3 hours, 15-minute break)
Date: 21/11/2026
Agenda
- Recap quiz on Session 3 (10 min)
- 4.1 Bias, confounding and causation (40 min)
- 4.2 Measuring disease and association, with a live 2x2 demo (25 min)
- Break (15 min), then two 2x2 calculations together (15 min)
- 4.3 Beyond single studies: tests, meta-analysis, appraisal (30 min)
- Proposal builder 4: exposure, outcomes, biases (40 min), then wrap-up (5 min)
Timetable
| Start | Clock* | Min | Segment |
|---|---|---|---|
| 0:00 | 19:30 | 10 | Recap quiz |
| 0:10 | 19:40 | 40 | 4.1 Bias, confounding and causation: random error vs bias, selection, information, confounding (by indication), effect modification, how designs fight bias, validity, reverse causation, Bradford Hill; spot-the-bias quiz |
| 0:50 | 20:20 | 25 | 4.2 Measuring disease and association: prevalence vs incidence, risk, 2×2, RR / OR / RD / NNT, OR vs RR; live 2×2 calculator demo |
| 1:15 | 20:45 | 15 | BREAK |
| 1:30 | 21:00 | 15 | Whole-class exercise: two 2×2 calculations, answers by poll |
| 1:45 | 21:15 | 30 | 4.3 Beyond single studies: diagnostic accuracy (sens/spec, PPV & prevalence, ROC), systematic reviews & forest plots, heterogeneity, risk-of-bias tools, “are the conclusions supported?” (whole-class task) |
| 2:15 | 21:45 | 40 | Proposal builder 4: outcomes, then modelled live (exposure & comparator, outcomes, main biases & mitigation); each participant drafts their own (finished as homework); three volunteers share in the chat |
| 2:55 | 22:25 | 5 | Wrap-up |
*Times are relative to the start of the session; the clock column shows Vietnam time for the online 19:30–22:30 session. All exercises are done by the whole class together (no groups). [DS] = course-dataset content (FLUID-ICU analysis and manuscript writing).
Slides
Press F for full screen, S for speaker notes, E to print, Esc for an overview.
Downloads
| Slides (PowerPoint) | English · Tiếng Việt |
| Exercise sheet | Read online · Word · PDF |
| Solutions | Read online · PDF |
| Live-demo script | Read online · PDF |
Before this session
- Your design, setting and population (Proposal Part 2, started after Session 3).
After this session (homework)
- Your proposal: finish Proposal Part 2 (exposure and comparator, outcomes, main biases and mitigation).
- Exercises B and D on the Session 4 sheet if not done in class (confounding or effect modification; PPV in two settings).