A t-test is a statistical test that is used to compare the means of two groups. ... statisticians use a z-test for data sets with a large sample size. ... Example of an Unequal Variance T-Test .

To test the effect of a larger sample size, two additional simulations were made using the parameter values that were shown to have low power when sample size was 25. Thus, r =0.009, N 0 =200, θ ...