# Dependent Sample T-test: 2-tailed

Large Effect Size

Power analysis for a dependent sample t-test was conducted in G*Power to determine a sufficient sample size using an alpha of 0.05, a power of 0.80, a large effect size (dz = 0.8), and two tails (Faul et al., 2013). Based on the aforementioned assumptions, the desired sample size is 15.

Medium Effect Size

Power analysis for a dependent sample t-test was conducted in G*Power to determine a sufficient sample size using an alpha of 0.05, a power of 0.80, a medium effect size (dz = 0.5), and two tails (Faul et al., 2013). Based on the aforementioned assumptions, the desired sample size is 34.

Small Effect Size

Power analysis for a dependent sample t-test was conducted in G*Power to determine a sufficient sample size using an alpha of 0.05, a power of 0.80, a small effect size (dz = 0.2), and two tails (Faul et al., 2013). Based on the aforementioned assumptions, the desired sample size is 199.

References

Faul, F., Erdfelder, E., Buchner, A., & Lang, A.-G. (2013). G*Power Version 3.1.7 [computer software]. Uiversität Kiel, Germany. Retrieved from http://www.psycho.uni-duesseldorf.de/abteilungen/aap/gpower3/download-and-register

Statistics Solutions. (2013). Sample Size Write-up [WWW Document]. Retrieved from http://www.statisticssolutions.com/resources/sample-size-calculator/dependent-sample-t-test-2-tailed/