Homework #3

Application Questions:

The previous Statistics classes at Delta State were required to take the Big Five Personality Inventory to predict success in the course. The previous courses openness scores gave the following descriptive statistics: =5.4 and =1.3. You are going to try to determine if your current class sample's (n=10) openness mean is statistically significantly different from the previous semesters' scores.

1.Step 1-State Hypotheses:

a.Null hypothesis (remember, this is the villain who doesn't believe in you):

b.Alternative hypothesis:

c.Would you use a one-tailed or two-tailed test?

2.Step 2- Set Decision Criterion:

a.Choose your level (your critical region):

3.Step 3- Make Up Data for your Sample's openness score:

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

4.Step 4- Calculate Statistics (show your work!):

a.What is your sample mean:

b.Compute standard error (pg. 178):

c.Run a z-test to get your new z-score(pg. 183):

d.Is your z-score in the critical region? (is it greater than 1.96 or less than -1.96)

5.Step 5- Make a Decision:

a.Do you reject or retain the null hypothesis (is it in the critical region)? (Does evil win?)

b.What does that mean about your sample's score on openness compared to previous semesters?

Conceptual Questions:

1.Let's say you used a sample size of n=40 for previous experiment. What would that change in your results?

2.What are the pros and cons of running a two-tailed test?

3.When we are conducting a one-sample z test why do we factor in standard error? What could happen if we didn't?

4.If a study claims to have a low standard error, what does that mean conceptually (don't just put the definition of standard error J)