Dr Kola Tytler (MBBS CertHE MBA MRCGP)|21 April 2026|7 min read
The statistics and evidence-based medicine section of the MRCGP AKT is only 10% of the exam — approximately 16 questions in the new 160-question format. But it accounts for a disproportionate share of AKT failures. The reason is straightforward: most GP trainees revise clinical medicine intensively and leave statistics until the final week, expecting to "pick it up" quickly. Statistics does not work that way.
The good news is that the AKT statistics syllabus is finite and predictable. The concepts are the same every year. A trainee who invests 15–20 hours in structured statistics revision can realistically score close to 100% on this section — which compensates for weaker performance elsewhere.
The Concepts You Must Know
Sensitivity and Specificity
Sensitivity is the probability that a test correctly identifies those with the disease (true positive rate). A highly sensitive test has few false negatives. "SnNOUT" — a sensitive test, when negative, rules out the disease.
Specificity is the probability that a test correctly identifies those without the disease (true negative rate). A highly specific test has few false positives. "SpPIN" — a specific test, when positive, rules in the disease.
You must be able to calculate both from a 2×2 table. Sensitivity = TP / (TP + FN). Specificity = TN / (TN + FP). This will appear on your exam.
Positive and Negative Predictive Value
PPV is the probability that a positive test result is a true positive. NPV is the probability that a negative test result is a true negative.
The critical concept: PPV and NPV are affected by prevalence. Even a test with excellent sensitivity and specificity will have a low PPV when prevalence is low (many false positives relative to true positives). This is why screening tests in low-prevalence populations generate more false positives than true positives — and the AKT loves testing this concept.
PPV = TP / (TP + FP). NPV = TN / (TN + FN).
Number Needed to Treat and Number Needed to Harm
NNT is the number of patients who need to be treated for one additional patient to benefit. NNT = 1 / ARR (absolute risk reduction). A smaller NNT indicates a more effective treatment.
NNH is the number of patients who need to be treated for one additional patient to experience harm. NNH = 1 / ARI (absolute risk increase).
The AKT will give you raw data (event rates in treatment and control groups) and expect you to calculate ARR and NNT. Know the formula and practise it.
Absolute vs Relative Risk Reduction
ARR = control event rate minus treatment event rate. RRR = ARR / control event rate, expressed as a percentage.
The AKT tests whether you understand the difference between "reduces risk by 50%" (RRR — impressive-sounding but potentially misleading) and "reduces risk from 2% to 1%" (ARR — small but real). Drug company marketing uses RRR; clinical decision-making should use ARR and NNT.
Study Design Hierarchy
You must recognise: systematic reviews and meta-analyses (highest level), randomised controlled trials, cohort studies, case-control studies, cross-sectional studies, case reports, and expert opinion (lowest level). Know the key features, strengths, and weaknesses of each design.
The AKT will present a study abstract and ask you to identify the study design, the main source of bias, or the most appropriate conclusion. Practise reading abstracts and identifying designs.
Common Biases
Selection bias, information bias (recall bias, observer bias), confounding, lead-time bias (in screening), length-time bias, and healthy volunteer effect. The AKT frequently tests whether a study's conclusions are valid by asking you to identify the bias that most threatens internal validity.
Screening Criteria
Wilson and Jungner screening criteria. The AKT tests whether a condition meets the criteria for a screening programme: important health problem, accepted treatment, facilities available, latent or early symptomatic stage, suitable test, acceptable to the population, natural history understood, agreed policy on treatment, economically balanced, and case-finding is a continuous process.
Forest Plots and Funnel Plots
Know how to interpret a forest plot: each horizontal line represents a study, the diamond represents the pooled estimate, and if the confidence interval crosses the line of no effect (1 for odds ratios, 0 for mean differences), the result is not statistically significant.
Know how to interpret a funnel plot: asymmetry suggests publication bias.
How to Revise Statistics
Do not rely on passive reading alone. Statistics requires active practice — calculation-based questions, critical appraisal exercises, and interpretation of data presentations.
Step 1: learn the concepts. Use a structured resource: the RCGP AKT statistics guide, the Zero to GP podcast statistics episodes, or the BMJ Learning EBM modules. Invest 3–4 hours in understanding the concepts before attempting any practice questions.
Step 2: practise calculations. Do 2×2 table calculations (sensitivity, specificity, PPV, NPV). Calculate NNT from raw data. Convert between absolute and relative risk. Do 5–10 calculation questions per day during your statistics revision phase.
Step 3: practise critical appraisal. Read study abstracts and identify: the design, the primary outcome, the main bias, and whether the conclusion is supported. Your Q-bank's statistics filter is your primary tool here.
Step 4: use iatroX's clinical AI for concept clarification. When you encounter a statistics concept you do not understand, query the AI — for example, "Explain the difference between odds ratio and relative risk" or "What is lead-time bias in screening?" — and receive an instant, clear explanation.
Resources for AKT Statistics
PassMedicine: filter AKT questions by the statistics/EBM domain for focused practice. The Knowledge Tutor covers statistics concepts.
iatroX: free AKT bank with adaptive targeting. If your statistics performance is weak, the algorithm will automatically resurface statistics questions at higher frequency. The clinical AI provides instant concept clarification.
Zero to GP podcast: free audio covering AKT statistics topics. Listen during commutes.
BMJ Learning: structured CPD-eligible EBM modules. Check if your Trust provides free access.
RCGP AKT statistics guide: syllabus-aligned statistics revision resource.
The Bottom Line
Sixteen questions. Finite, predictable concepts. High-yield revision. The statistics section is the single most improvable component of the AKT. Invest the time.
Information based on the 2025 RCGP curriculum and public sources as of 21 April 2026. Trademarks belong to their owners.