1. Calculating sample size for means Afshin Ostovar Bushehr University of Medical Sciences

2. Principles of Sample Size 1. Variability 2. Effect size 3. Significance level 4. Power of the test 5. Type of the test

3. Type of the test  Estimation of a mean  Comparing with a constant  Comparing two independent means  Comparing two dependent means  Comparing many independent means

4. Type of the test  Estimation of a mean  Comparing with a constant  Comparing two independent means  Comparing two dependent means  Comparing many independent means

5. Estimation of mean Variability Significance Level Difference Standardized effect size

6. Type of the test  Estimation of a mean  Comparing with a constant  Comparing two independent means  Comparing two dependent means  Comparing many independent means

7. Comparing with a constant Variability Difference Standardized effect size Significance Level Power of the Test

8. Type of the test  Estimation of a mean  Comparing with a constant  Comparing two independent means  Comparing two dependent means  Comparing many independent means

9. Comparing two independent groups Variability Difference Standardized effect size Significance Level Power of the Test Mean in group 1 Mean in group 2

10. Type of the test  Estimation of a mean  Comparing with a constant  Comparing two independent means  Comparing two dependent means  Comparing many independent means

11. Comparing Dependent Means Variability Difference Standardized effect size Significance Level Power of the Test

12. Comparing Dependent Means Variability Difference Standardized effect size Significance Level Power of the Test Mean in group 1 Mean in group 2

13. Type of the test  Estimation of a mean  Comparing with a constant  Comparing two independent means  Comparing two dependent means  Comparing many independent means

14. Comparing many independent means 1. Calculate effect size: d = δ/σ 2. Adjustment to formula

15. Adjustment of effect size