Question

Two samples each with n= 15 individuals are used to evaluate the difference
between two treatment conditions. If the researcher uses a two-tailed test with
α = .05, then the critical region for the t statistic begins at _________?

a. t = + 2.145

b. t = + 2.131

c. t = + 2.048

d. t = + 2.045

Answer 1

The critical T -score is calculated using the excel formula for T-distribution which takes the significance level, degree of freedom and the type of hypothesis as parameters.

Since the significance level is given as 0.05, the degree of freedom is calculated as df = n1+n2-2 where n1 and n2 are the sample size of both the sample respectively, so df = 15+ 15 -2 = 28 and the type of test is a two-tailed test.

The formula used is =T.INV.2T(0.05,28), this results in Tc = +2.048

So,

c. t = + 2.048