1. What is meant by "the difference of the means" when talking about an independent samplesttest? How does it differ from the "mean of the differences" in a related samplesttest?
2. Describe three research questions that could be tested using an independent samplesttest.
3. Calculate pooled variance from the following raw data:

Group 1	Group 2
16	4
11	10
9	15
7	13
5	12
4	9
12	8

1. Calculate the standard error from the following descriptive statistics.
   1. s₁= 24,s₂= 21,n₁= 36,n₂= 49
   2. s₁= 15.40,s₂= 14.80,n₁= 20,n₂= 23
   3. s₁= 12,s₂= 10,n₁= 25,n₂= 25
2. Determine whether to reject or fail to reject the null hypothesis in the following situations:
   1. t(40) = 2.49,a= .01, one-tailed test to the right
   2. = 64,= 54,n₁= 14,n₂= 12,= 9.75,a= .05, two-tailed test
   3. 95% CI: (0.50, 2.10)
3. A professor is interested in whether the type of software program used in a statistics lab affects how well students learn the material. The professor teaches the same lecture material to two classes but has one class use a point-and-click software program in lab and has the other class use a basic programming language. The professor collects final exam scores for students in each class. Conduct a hypothesis test to answer the research question.

Point-and-Click	Programming
83	86
83	79
63	100
77	74
86	70
84	67
78	83
61	85
65	74
75	86
100	87
60	61
90	76
66	100
54

1. A researcher wants to know if there is a difference in how busy someone is based on whether that person identifies as an early bird or a night owl. The researcher gathers data from people in each group, coding the data so that higher scores represent higher levels of being busy, and tests for a difference between the two at the .05 level of significance. Conduct a hypothesis test to answer the research question.

Early Bird	Night Owl
23	26
28	10
27	20
33	19
26	26
30	18
22	12
25	25
26

1. Lots of people claim that having a pet helps lower their stress level. Use the following summary data to test the claim that there is a lower average stress level among pet owners (Group 1) than among non-owners (Group 2) at the .05 level of significance.
   • = 16.25,= 20.95,s₁= 4.00,s₂= 5.10,n₁= 29,n₂= 25
2. Administrators at a university want to know if students in different majors are more or less extroverted than others. They provide you with descriptive statistics they have for English majors (coded as 1) and History majors (coded as 2) and ask you to create a confidence interval of the difference between them. Does this confidence interval suggest that the students from the majors differ?
   • = 3.78,= 2.23,s₁= 2.60,s₂= 1.15,n₁= 45,n₂= 40
3. Researchers want to know if people's awareness of environmental issues varies as a function of where they live. Use the following summary data from two states, Alaska and Hawaii, to test for a difference.

• = 47.50,= 45.70,s_H= 14.65,s_A= 13.20,n_H= 139,n_A= 150