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Sample Size Calculator (web)

2 means (paired) - Hypothesis Testing^1,2

Standard deviation of difference (σ_d)*:

If σ_d not available in literature, use Standard deviation of difference calculator below to get an approximate value of σ_d. Expected difference:
Significance level (α): Two-tailed
Power (1 - β): %
Expected dropout rate: %

Sample size, n =
Sample size (with 10% dropout), n_drop =

Standard deviation of difference, σ_d²

Standard deviation at Pre intervention (σ_pre):

Standard deviation at Post intervention (σ_post):

Correlation between pre and post:

Standard deviation of difference (σ_d) =

Formula reference:

¹Naing, N. N. (2011). A practical guide on determination of sample size in health sciences research. Kelantan: Pustaka Aman Press.

²Arifin, W. N. (2014). Calculating standard deviation of difference for determination of sample size for planned paired t-test analysis. Education in Medicine Journal, 6(2), e62-e64.

Suggested reference:

APA: Arifin, W. N. (). Sample size calculator (web). Retrieved from http://wnarifin.github.io

Vancouver: Arifin WN. Sample size calculator (web) [Internet]. [cited ]. Available from: http://wnarifin.github.io

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