Key points
- AKT EBM/data questions are often <strong>method questions</strong>, not medicine questions: your job is to interpret what’s shown (denominator, axis, rate vs count).
- Use a <strong>repeatable 6-step scan</strong> for every chart/table before you even look at the answer options.
- Most lost marks come from: <strong>rates vs totals</strong>, <strong>relative vs absolute risk</strong>, and misreading <strong>confidence intervals</strong>.
The mental model
Step 1 — Identify the unit of meaning (10 seconds)
Step 2 — Read the axes like a lawyer (15 seconds)
Step 3 — Convert the figure into one sentence (10 seconds)
Step 4 — Separate association from causation (10 seconds)
Step 5 — Use the CI rule properly (10 seconds)
Step 6 — Translate relative risk into absolute impact (30 seconds)
The AKT Data Question “Trap List” (memorise this)
- Rate vs count: “per 1,000” is not the same as “number of events”.
- Proportion vs number: a higher proportion can occur with fewer absolute events (different denominators).
- Correlation ≠ causation: do not infer interventions caused outcomes from cross-sectional audit-style charts.
- CI ≠ range of patient outcomes: it’s uncertainty around the estimate, not variability in individuals.
- p-value ≠ clinical relevance: significance does not mean “worth doing”.
- Screening metrics: sensitivity/specificity are test properties; PPV/NPV depend on prevalence.
What to do when you feel unsure
The 20-minute weekly drill (high ROI)
Build a micro-cheat-sheet (one page only)
Save your place and choose what comes next
Work through this guide (14 steps)
Use the actions from this article to track what you have worked through.
Sign in using the reading controls above to save your steps.
Before reading options, state the unit out loud: rate per 1,000, percentage, incidence, odds ratio, hazard ratio, absolute number. Many “trick” questions are just denominator traps.
Return to this sectionConfirm: axis labels, time window, population, whether the plot is per 1,000 / per 100,000, whether it is log scale, whether there’s a second axis, and whether the plotted values are adjusted or raw.
Return to this sectionWrite (mentally): “In population X, outcome Y is higher/lower in group A vs B over time T.” If you cannot summarise in one sentence, you are not ready to answer.
Return to this sectionIf it’s observational: default to association, consider confounding and bias. If it’s RCT/meta-analysis: consider randomisation, effect size, and certainty.
Return to this sectionFor ratios (RR/OR/HR): CI crossing 1 → not statistically significant at that level. For differences (mean difference): CI crossing 0 → not statistically significant. Then ask: even if significant, is it clinically meaningful?
Return to this sectionIf you can estimate baseline risk, convert to absolute risk reduction and then NNT (NNT ≈ 1 / ARR). The AKT likes testing whether you can spot when a “big relative risk” is actually small absolute benefit.
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Once weekly, do 10 AKT-style data questions timed. For each wrong answer, write a one-line error label (e.g., “denominator trap”, “CI crossing 1”, “association/cause confusion”). After 4 weeks, your pattern will be obvious—and fixable.
Return to this sectionYour one page should contain: CI rule, RR→ARR→NNT conversion, sensitivity vs PPV, and 5 most common graph traps. If it becomes 3 pages, you have lost the point.
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Study methods · Article 23 of 48