1. Some people say that a paired t-test is just a one-sample t-test. Why? Think about the calculations of the paired t-test and one-sample t-test, and explain how they are related.

2. We usually compare the calculated p value with 0.05. What does 0.05 mean? Why can we reject the null hypothesis if the calculated p values is smaller than 0.05 (you can use sentences or drawings to answer this question).

3. This is an extra-credit question (1 in addition to 15 points).

Nowadays most journals prefer the study that can reject null hypothesis than the one that cannot. Is there any particular reason that people don't like studies that cannot reject the null hypothesis? What are your thoughts about null results studies? (Hint: think about how null hypothesis testing works.)