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Use the study example below for Questions #1-5. Imagine I wanted to…
Use the study example below for Questions #1-5.
Imagine I wanted to study the effectiveness of the Mediterranean diet on people’s memory.
I tested a group of people who strictly followed the Mediterranean diet, another group who
followed a typical Western diet, and another whose diet I did not change at all. Before the
diet changes began, I gave all my participants a memory test. After six weeks of the diet
experiment, I had all participants complete the same memory test again to see how scores
would change among the three groups.
1. For this study, identify a parameter and a statistic I might be interested in.
2. Identify the independent and dependent variables.
3. What is a methodological technique I would need to use in this study to ensure that
any difference I find between groups is due to my experimental manipulation only?
4. Identify a variable of categorical data and a variable of measurement/quantitative
data in this study.
5. At some point I would need to statistically analyze this data to actually see if
participants’ diet changed their memory test scores. We discussed a decision tree
that can help us decide which statistical test is appropriate for a given dataset. Use
this to make the first three decisions about how to answer the research question in
this study. Include a) each of the three decisions you have to make and b) the
response to each decision.
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6. Give an example where the number 18 would be on an interval scale but not a ratio
scale. (You can’t use temperature as your example.)
7. We mentioned (ch 2) that we often treat a discrete variable as if it were continuous.
Under what conditions would we be likely to do so?
Use the study example below for Questions #8-15.
In a study of the moon illusion (which we will discuss later), Kaufman and Rock (1962)
tested a hypothesis about reasons for the moon illusion by comparing how observers
performed when they were able to look at the moon with their eyes level, and again with
their eyes elevated.
The data for the Eyes Level condition (represented as X) was:
1.65 1.00 2.03 1.25 1.05 1.02 1.67 1.86 1.56 1.73
The data for the Eyes Elevated condition (represented as Y) was:
1.73 1.06 2.03 1.40 0.95 1.13 1.41 1.73 1.63 1.56
8. Calculate SX and SY.
9. What are Y1 and Y10?
10. Calculate (SY)2 and SY2.
11. Calculate (SX)(SY).
12. Use this data to show that SXY ? SXSY. (? means “does not equal.”)
13. Use this data to show that SCX = CSX, where C = 5.
14. Calculate SX/N, where N = the number of scores in X.
15. What do you call the answer to #14?
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Use the excerpt below for Questions #16-20.
The Journal of Public Health published data on the relationship between smoking and
health. They reported the cigarette consumption per adult for 21 mostly Western countries,
along with the coronary heart disease rate for each country. The data clearly show that
coronary heart disease is highest in those countries with the highest cigarette consumption.
16. How would you characterize the two variables in this study in terms of what we
have labeled “scales of measurement”?
17. What other variables might need to be taken into consideration in such a study?
18. Give an example of a descriptive statistic in this study.
19. Give an example of an inferential statistic in this study.
20. Do a quick Google search to find articles relating secondhand smoke to coronary
heart disease. What do these articles suggest? (Provide at least 3 complete sentences
and link at least one article below. This does not need to be a peer-reviewed article.
