Explore BrainMass
Share

# Designing an experiment

This content was STOLEN from BrainMass.com - View the original, and get the already-completed solution here!

"We are interested in whether higher levels of physical activity are associated with lower cholesterol levels"

1. First I need to figure out how to measure those two variables??

2. Then they want me to design an ex-post facto (quasi-experimental) study...but i still have no idea what that is.. how would I go about doing that?

https://brainmass.com/statistics/designing-studies/designing-an-experiment-41642

#### Solution Summary

By responding to the questions, this solution assists in designing a study investigating whether higher levels of physical activity are associated with lower cholesterol levels. Supplemented with an artcile describing how to design a study.

\$2.19

## Statistics Questions - quasi-experiments

A. Complete Jackson Even-numbered chapter exercises, p, 360

1Describe the advantages and disadvantages of quasi-experiments? What is the fundamental weakness of a quasi-experimental design? Why is it a weakness? Does its weakness always matter?
2If you randomly assign participants to groups, can you assume the groups are equivalent at the beginning of the study? At the end? Why or why not? If you cannot assume equivalence at either end, what can you do? Please explain.
3Explain and give examples of how the particular outcomes of a study can suggest if a particular threat is likely to have been present.
4Describe each of the following types of designs, explain its logic, and why the design does or does not address the selection threats discussed in Chapter 7 of Trochim and Donnelly (2006):
Non-equivalent control group pretest only
Non-equivalent control group pretest/posttest
Cross-sectional
Regression-Discontinuity
5Why are quasi-experimental designs used more often than experimental designs?
6One conclusion you might reach (hint) after completing the readings for this assignment is that there are no bad designs, only bad design choices (and implementations). State a research question for which a single-group post-test only design can yield relatively unambiguous findings.

Part II - Answer the following questions:
1What research question(s) does the study address?
2What is Goldberg's rationale for the study? Was the study designed to contribute to theory? Do the results of the study contribute to theory? For both questions: If so, how? If not, why not?
3What constructs does the study address? How are they operationalized?
4What are the independent and dependent variables in the study?
5Name the type of design the researchers used.
6What internal and external validity threats did the researchers address in their design? How did they address them? Are there threats they did not address? If so how does the failure to address the threats affect the researchers' interpretations of their findings? Are Goldberg's conclusions convincing? Why or why not?
Support your paper with a minimum of 5 resources

View Full Posting Details