Research Methodology, Biostatistics and Evidence-Based Practice
Research Methodology, Biostatistics and Evidence-Based Practice
This domain tests your ability to critically appraise literature and apply evidence to clinical practice. You must understand study designs (randomized controlled trials, cohort, case-control, cross-sectional), measures of association (odds ratio, relative risk), and statistical tests (t-test, chi-square, ANOVA). Also, know the levels of evidence and grades of recommendation. Key concepts include sensitivity, specificity, positive predictive value, and confidence intervals. Evidence-based practice involves formulating a PICO question, searching for evidence, appraising it, and applying it.
Traps: Questions often test the difference between odds ratio (case-control) and relative risk (cohort). Another trap is type I vs type II error: type I is false positive (alpha), type II is false negative (beta). Also, know that p-value <0.05 is statistically significant, but does not indicate clinical significance. For diagnostic tests, sensitivity is the ability to detect disease; specificity is the ability to rule out disease.
Rule of thumb: For a diagnostic test, use SnNout (high sensitivity, negative result rules out) and SpPin (high specificity, positive result rules in). For study design, RCT is the gold standard for intervention studies.
Worked example: A study reports an odds ratio of 2.5 for smoking and oral cancer. This means smokers have 2.5 times the odds of oral cancer compared to non-smokers. However, odds ratio overestimates relative risk when the outcome is common.