1. What is the difference between a one-samplettest and a related-samplesttest? How are theyalike?
2. Name three research questions that could be addressed using a related-samplesttest.
3. What are difference scores and why do we calculate them?
4. Why is the null hypothesis for a related-samplesttest always_D= 0?
5. A researcher is interested in testing whether explaining the processes of statistics helps increase trust in computer algorithms. He wants to test for a difference at thea= .05 level and knows that some people may trust the algorithmslessafter the training, so he uses a two-tailed test. He gathers pre-post data from 35 people and finds that the average difference score is= 12.10 with a standard deviation ofs_D= 17.39. Conduct a hypothesis test to answer the research question.
6. Decide whether you would reject or fail to reject the null hypothesis in the following situations:
   1. = 3.50,s_D= 1.10, n = 12,a= .05, two-tailed test
   2. 95% CI = (0.20, 1.85)
   3. t= 2.98,t* = 2.36, one-tailed test to the left
   4. 90% CI = (1.12, 4.36)
7. Calculate difference scores for the following data:

Time 1	Time 2	XD
61	83
75	89
91	98
83	92
74	80
82	88
98	98
82	77
69	88
76	79
91	91
70	80

1. Researchers investigated the extent to which Japanese immigrant mothers encouraged their infants to interact with them or with objects in their environment (such as toys). The researchers observed 8 mothers with their infants. Data are the number of times that mothers encouraged their infants to engage with them or with objects during the observation period. Test the hypothesis at thea= .05 level using the four-step hypothesis testing procedure.

With Mom	With Objects
15	40
12	47
14	32
10	50
20	35
28	45
12	42
15	32

1. Construct confidence intervals from a mean of= 1.25, standard error of= 0.45, anddf=10 at the 90%, 95%, and 99% confidence levels. Describe what happens as confidence changes and whether to rejectH₀.
2. A professor wants to see how much students learn over the course of a semester. A pre-test is given before the class begins to see what students know ahead of time, and the same test is given at the end of the semester to see what students know at the end. The data are below. Test for an improvement at thea= .05 level. Did scores increase? How much did scores increase?

Pre-test	Post-test	XD
90	89
60	66
95	99
93	91
95	100
67	64
89	91
90	95
94	95
83	89
75	82
87	92
82	83
82	85
88	93
66	69
90	90
93	100
86	95
91	96