A school psychologist is interested in whether a particular remedial math training program helps improve students' math skills. He randomly assigns 18 students to one of two groups: remedial training or no intervention. At the end of the training program, he administers a 100 point math test to all students, and counts the number of errors made by students in each group. These data (number of errors per student) are shown below.

NO INTERVENTION REMEDIAL TRAINING

18 12

15 6

17 8

13 13

15 12

19 6

22 10

19 7

20 11

SS₁ = 64.22222 11 SS₂ = 60.22222

X₁ = 158 X₂ = 85

(a) What type of t-test should be used?

(b) What is the null and alternative hypotheses

(c) State your df AND critical values of t, with =.05; assume a two-tailed test

(d) Calculate t

(e) State whether or not the null hypothesis should be rejected

(f) Give a brief sentence summarizing the outcome of this null hypothesis test in terms of the research question.