Sample Size Estimation Made Simple: Every Formula + Worked Examples

How many participants does your study really need? 🤔 Too few and you miss real effects. Too many and you waste time, money and participants’ effort. In this lecture, Prof. Dr. Asif Hanif walks you step by step through sample size estimation for health and medical research, from the key concepts to the right formula for each study design, with worked examples. You’ll learn: ✅ Population, sample, alpha, confidence level, power, prevalence and precision ✅ Probability vs non-probability sampling ✅ Z values for confidence and power (1.96, 0.84, 1.28…) ✅ How the study objective decides the design, and the design decides the formula ✅ Formulas for prevalence, correlation, two proportions, means, case-control and diagnostic accuracy studies ✅ 4 worked examples: foot ulcer prevalence, folic acid and fetal anomalies, fetal renal length, and ultrasound accuracy for ovarian masses ✅ Software that can help, and why you should always add an allowance for dropouts Note: the numbers in the worked examples are illustrative values for teaching, not results from a specific study. Chapters 0:00 Intro 0:12 Why sample size matters 0:47 Why sampling? 1:10 Important concepts 2:08 Sampling methods 2:36 Confidence, alpha and Z values 3:12 What information do you need? 3:46 Objective → study design 4:20 Population size known & correlation 5:05 Estimating a prevalence 5:30 Two proportions 6:00 Estimating & testing a mean 6:33 Comparing means & case-control studies 7:02 Diagnostic accuracy 7:39 Practice: prevalence of foot ulcer 8:26 Practice: folic acid & fetal anomalies 9:04 Practice: fetal renal length 9:35 Practice: diagnostic accuracy of ultrasound 10:17 Software for sample size 10:49 Putting it all together 👨‍🏫 Prof. Dr. Asif Hanif, Professor of Biostatistics, Sakarya University, Türkiye 🎬 Asif AI Studio: biostatistics, research methods and AI for health research 👍 Like · 💬 Comment · 🔁 Share · 🔔 Subscribe · 📌 Save #SampleSize #Biostatistics #ResearchMethods #MedicalResearch #AsifAIStudio