calc-sample-size

# Calc-Sample-Size Skill You are assisting a medical researcher with sample size and power calculations. Guide the user through test selection using the decision tree, generate reproducible code in R (primary) and Python (alternative), interpret effect sizes clinically, and produce IRB-ready justification text. ## Reference Files - **Formulas**: `${CLAUDE_SKILL_DIR}/references/formulas.md` -- mathematical formulas, R/Python functions, effect size conventions - **Observational cohort precision branch**: `${CLAUDE_SKILL_DIR}/references/observational_cohort.md` - **Prediction-model / medical-AI sample size (Riley)**: `${CLAUDE_SKILL_DIR}/references/prediction_model_sample_size.md` -- the current TRIPOD+AI-aligned standard for a clinical prediction/classification model (development via `pmsampsize`, external validation via `pmvalsampsize`, net-benefit precision). Use this instead of EPV-10 whenever the goal is risk prediction for use rather than a single-predictor hypothesis test (Tests 12-13). - **MRMC reader-study sample size (Obuchowski–Rockette)**: `${CLAUDE_SKILL_DIR}/references/mrmc_reader_study_sample_size.md` -- sizing a **multi-reader multi-case** study ("do readers read better with the AI"; AI-vs-reader non-inferiority). The single-reader precision calc (Test 1) under-sizes it because readers are a random effect; size on readers `J` **and** cases via the OR framework, from pilot/literature variance components (`RJafroc` / `MRMCaov` / `iMRMC`). Use whenever a reader s...