Part -1:

1) To test the hypothesis in Exercise 1, the admissions counselors select a random sample of freshman and compare their scores on the SAT to those of the population of upperclassmen. They find that the freshman do in fact have a higher mean SAT score. However, what they are unaware of is that the sample of the freshman was not representative of all freshman at Brainy University. In fact, the sample overrepresented those with high scores and underrepresented those with low scores. What type of error (Type I or Type II) did the counselors make?

2) What are the appropriate Ho and Ha for each of the following research studies? In addition, note whether the hypothesis test is one- or two-tailed.

a) A study in which researchers want to test whether there is a difference in spatial ability between left- and right-handed people.

b) A study in which researchers want to test whether nurses who work 8-hour shifts deliver higher-quality work than those who work 12-hour shifts.

c) A study in which researchers want to determine whether crate-training puppies is superior to training without a crate.

Part -2:

1) What is the standard error in the difference between means?

2) A college student is interested in whether there is a difference between male and female students in the amount of time spent studying each week. The student gathers information from a random sample of male and female students on campus. Amount of time spent studying is normally distributed.

The data follow:

Males               Females

27                    25

25                    29

19                    18

10                    23

16                    20

22                    15

14                    19

a) What statistical test should be used to analyze the data?

b) Identify Ho and Ha for this study.

c) Conduct the appropriate analysis.

d) Should Ho be rejected? What should the researcher conclude?

e) If significant, compute the effect size and interpret.

f) If significant, draw a graph representing the data.