Question

state the critical values for a two-independent same t-test given the following conditions:

a. two-tailed test a=.01, total df=26

b. one-tailed test, lower tail critical a=.01,df=15 for each group

c. two- tailed test, a=.05, n=12 in each group

d.one-tailed test, upper tail critical, a=.05 n for both groups combined is 30

Answer 1

a) For 26 degrees of freedom, we get from the t distribution tables:

P( t26 < 2.779) = 0.995

Therefore, P( -2.779 < t26 < 2.779) = 0.99

Therefore -2.779, 2.779 are the critical values here.

b) For a one tailed test, for 15 degrees of freedom, we get from the t distribution tables:

P( t15 < -2.602 ) = 0.01

Therefore -2.602 is the required critical t value here.

c) For n - 1 = 11 degrees of freedom, we get from the t distribution tables that:
P( t11 < 2.201) = 0.975

Therefore -2.201, 2.201 are the required critical values here.

d) For n - 2 = 28 degrees of freedom, we get from the t distribution tables:

P( t28 < 1.701) = 0.95

Therefore 1.701 is the required critical value here.