An instructor is interested in checking whether attending labs improves students' performance on their finals. The instructor asks a TA to investigate this problem. The TA decides to conduct a one-sided two sample t-test. He randomly chooses 30 students in the course who never missed a lab, as well as 25 students from the same course who missed at least 1 lab. Let ?1 denote the mean final exam score of all students in the course who never missed a lab. Let ?2 denote the mean final exam score of all students in the course who missed at least 1 lab. The hypothesis test can be formulated as H0:?1=?2 vs HA:?1>?2. The P-value is 0.001.

Part a) What type of study is this?

An experiment with a matched pairs design.

An experiment with a randomized block design.

An observational study.

An experiment with a completely randomized design.

Part b) What can we conclude from this study? (Select all that apply)

A. Since the null hypothesis is rejected at 5% level, the TA can report to the instructor that there is sufficient evidence to show attending labs improves performance on finals.

B. Since the P-value is very small, the TA can report to the instructor that there is strong evidence to show attending labs improves performance on finals.

C. There is insufficient evidence to answer the instructor's question.