Sample Size Determination

This is a free website you can use to determine sample size for your research project.

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Sample Size Determination
Purpose	Objective
Estimation of a parameter with specified precision	Estimation of a mean with specified precision	Estimation of a proportion / prevalence with specified precision
Estimation of difference with specified precision	Estimation of difference between two means with specified precision	Estimation of difference between two proportions with specified precision
Estimation of an effect size in Case Control or Cohort study with specified precision	Estimation of Odds Ratio in Case Control Study with specified precision	Estimation of Relative Risk in Cohort Study with specified precision
	Estimation of Pearson's Correlation Coefficient with specified precision	Estimation of Kappa statistics with specified precision
Hypothesis Testing - One Sample	Significant difference between sample mean and hypothetical / known value	Significant difference between sample proportion and hypothetical / known value
Hypothesis Testing - Two independent Samples	Significant difference between two sample means	Significant difference between two sample Proportions
Hypothesis Testing - More than Two independent Samples	Significant difference between more than two sample means (ANOVA)	Significant difference between more than two sample proportions (m x n table) (Chi square test of independence) Significant difference between group proportions and expected / known proortions(Chi square test of Goodness of fit)
Clinical Trial - Superiority Design	Outcome variable: Ratio	Outcome variable: Nominal
Clinical Trial - Non-Inferiority Design	Outcome variable:Ratio	Outcome variable: Nominal
Clinical Trial - Equivalence Design	Outcome variable:Ratio	Outcome variable: Nominal
Case-Control or Cohort Studies	Odds Ratio is Significantly different than 1 (Significant OR)	Relative Risk is Significantly different than 1 (Significant RR)
Other Situations	Evaluation of a diagnostic test
Simple or Multiple Linear Regression.	Simple or Multiple Linear Regression. (R squared > 0)	Simple or Multiple Linear Regression. (Change in R squared > 0, when more predictors are added.)

Sample Size Determination: Help
Purpose	Objective
Estimation of a parameter with specified precision	Estimation of a mean with specified precision	Estimation of a proportion / prevalence with specified precision
Estimation of an effect size in Case Control or Cohort study with specified precision	Estimation of Odds Ratio in Case Control Study with specified precision	Estimation of Relative Risk in Cohort Study with specified precision
	Estimation of Pearson's Correlation Coefficient with specified precision	Estimation of Kappa statistics with specified precision
Hypothesis Testing - One Sample	Significant difference between sample mean and hypothetical / known value	Significant difference between sample proportion and hypothetical / known value
Hypothesis Testing - Two independent Samples	Significant difference between two sample means	Significant difference between two sample Proportions
Hypothesis Testing - More than Two independent Samples	Significant difference between more than two sample means (ANOVA)	Significant difference between more than two sample proportions (m x n table) (Chi square test of independence) Significant difference between group proportions and expected / known proortions(Chi square test of Goodness of fit)
Clinical Trial - Superiority Design	Outcome variable: Ratio	Outcome variable: Nominal
Clinical Trial - Non-Inferiority Design	Outcome variable:Ratio	Outcome variable: Nominal
Clinical Trial - Equivalence Design	Outcome variable:Ratio	Outcome variable: Nominal
Case-Control or Cohort Studies	Odds Ratio is Significantly different than 1 (Significant OR)	Relative Risk is Significantly different than 1 (Significant RR)
Other Situations	Evaluation of a diagnostic test
Simple or Multiple Linear Regression.	Simple or Multiple Linear Regression. (R squared > 0)	Simple or Multiple Linear Regression. (Change in R squared > 0, when more predictors are added.)