PSY520 Graduate Statistics
Week 1 Discussion
DQ1 Review the levels of measurement terms in the Statistics Visual Learner media piece. Compare and contrast Stevens’s four scales of measurement, and explain when each type of scale should be used.
DQ2 The professor teaching a large introductory class gives a final exam that has alternate forms, A, B, and C. A student taking the exam using Form B is upset because she claims that Form B is much harder than Forms A and C. Discuss how percentile point data might be useful to determine if the student is correct.
PSY520 Graduate Statistics
Week 2 Discussion
DQ1 The process of random sampling guarantees that the sample selected will be representative of the population. Is this statement true? Discuss.
DQ2 Review the video on Normal Distribution in the Calculations section of the “Statistics Visual Learner” media piece.
Bob compares his SAT Verbal score of 400 to Marge’s ACT Verbal score of 20. “I beat you,” he exclaims. “My score is 20 times your score!” Although his multiplication is good, his logic is faulty. Explain why.
PSY520 Graduate Statistics
Week 3 Discussion
DQ1 Review the video “Linear Correlation” in the Calculations section of the “Statistics Visual Learner” media piece.
It is sometimes said that the higher the correlation between two variables, the more likely the relationship is causal. Do you think this is correct? Discuss.
DQ2 Discuss the strengths and weaknesses of correlational and regression studies; discuss concepts such as positive and negative correlations, correlation coefficients, confounding, and causality.
PSY520 Graduate Statistics
Week 4 Discussion
DQ1 Explain why there is an inverse relationship between committing a Type I error and committing a Type II error. What is the best way to reduce both kinds of error?
DQ2 Review the term Significance Test in the “Statistics Visual Learner” media piece.
When a newspaper or magazine article reports the results of a study and draws a conclusion without also reporting whether the results are statistically significant, what are the possible reasons for doing so? How seriously should you take the conclusion offered in such a study? Discuss.
PSY520 Graduate Statistics
Week 5 Discussion
DQ1 Explain why using the t statistic may be an appropriate alternative to using a z-score (use the concept of estimated standard error to justify your answer).
DQ2 Discuss how the t-test for correlated groups and the t-test for single samples are alike and different.
PSY520 Graduate Statistics
Week 6 Discussion
DQ1 Review the four “ANOVA” videos in the Calculations section of the “Statistics Visual Learner” media piece.
Explain the major differences between analyzing a one-way ANOVA versus a two-factor ANOVA, and explain why factorial designs with two or more independent variables (or factors) can become very difficult to interpret.
DQ2 plain how the ANOVA technique avoids the problem of the inflated probability of making Type I error that would arise using the alternative method of comparing groups two at a time using the t-test for independent groups.
PSY520 Graduate Statistics
Week 7 Discussion
DQ1 Review the three “Non-parametric” test videos in the Calculations section of the “Statistics Visual Learner” media piece.
A researcher is examining preferences among four new flavors of ice cream. A sample of n = 80 people is obtained. Each person tastes all four flavors and then picks a favorite. The distribution of preferences is as follows. Do these data indicate any significance preferences among the four flavors? Test at the .05 level of significance.
Ice Cream Flavor
A
B
C
D
12
18
28
22
DQ2 Is it true that parametric tests are generally more powerful than nonparametric tests? If so, give two reasons why you might choose to use a nonparametric test instead of a parametric test.
PSY520 Graduate Statistics
Week 8 Discussion
DQ1 To determine whether a new sleeping pill has an effect that varies with dosage, a researcher randomly assigns adult insomniacs, in equal numbers, to receive either 4 or 8 grams of the sleeping pill. The amount of sleeping time is measured for each subject during an 8-hour period after the administration of the dosage. What type of design is this, and what type of statistic is needed to analyze the data?
DQ2 Dr. Bill Board designs a 2 X 2 between-subjects factorial design, where Factor A is word frequency (low or high) and Factor B is category cues (no cues or cues). Assume that the data are interval. What type of statistic is needed to analyze the data?
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