Assignment task:
Correlational research, which you explored in this week's Discussion, is useful in identifying relations between two variables. But correlational research does not answer questions regarding "cause and effect" among the variables because researchers did not control for outside factors. As you have explored in previous weeks, to demonstrate possible causal relations among variables, researchers will need to manipulate variables in an experimental research design.
In previous weeks, you have practiced generating a hypothesis. Another step in becoming a skilled researcher is possessing sound knowledge of theoretical concepts related to testing a hypothesis to determine if it is plausible. In this Assignment, you will apply key concepts related to experimental design, including hypothesis testing, applying inferential statistics, and analyzing and interpreting the outcome of the study. Need Assignment Help?
Be sure to review the Learning Resources before completing this activity.
Readings:
Review previous chapters if you need to (e.g., Chapter 2 on hypotheses and predictions and/or Chapter 4 on nonexperimental versus experimental research, independent and dependent variables, etc.)
Cozby, P. C., & Bates, S. C. (2024). Methods in behavioral research (15th ed.). McGraw Hill.
Chapter 13, "Understanding Research Results: Statistical Inference"
To prepare:
Read Chapter 13 and review previous chapters for additional support, if necessary.
Read the following study scenario:
Researchers are interested in the effectiveness of a particular treatment for insomnia. They contacted 50 insomnia sufferers who responded to a newspaper advertisement to participate in the study. Each participant is given a pill with instructions to take it before going to sleep that night. The pill contains milk powder (a placebo). The participants are randomly assigned to receive one of two sets of instructions about the pill. One half of the participants is told that the pill will make them feel "sleepy," and the other half is told that the pill will make them feel "awake and alert." The next day, the participants return to the lab and are asked to indicate how long it took them to fall asleep after taking the pill. The individuals who were told that the pill would make them feel sleepy reported that they fell asleep faster than the participants who were told the pill would make them feel alert.
As needed, review Learning Resources from previous weeks about hypothesis testing and identification of independent and dependent variables in a hypothesis.
Think about how this week's concepts apply to the study above.
Null hypothesis
Research hypothesis (also termed alternative hypothesis)
Type I and Type II errors
Be sure to review the Learning Resources before completing this activity.
Review previous chapters if you need to (e.g., Chapter 2 on hypotheses and predictions and/or Chapter 4 on nonexperimental versus experimental research, independent and dependent variables, etc.)
Cozby, P. C., & Bates, S. C. (2024). Methods in behavioral research (15th ed.). McGraw Hill.
Chapter 13, "Understanding Research Results: Statistical
Inference"
Readings:
Analysis of variance (ANOVA)
Statistical significance and effect size
Submit a 1- to 2-page paper that responds to the following:
With the study scenario in mind, do the following:
- Identify the independent variable and dependent variable.
- State the null hypothesis and the alternative hypothesis.
- Explain what the researchers would conclude if a Type I error occurred in this study.
- Explain what the researchers would conclude if a Type II error occurred in this study.
Note: Until this point, there have been two conditions in the study scenario.
Next, presume a third condition was added to the study in which participants are not given any information about the effects of the (placebo) pill. Suppose an analysis of variance (ANOVA) was conducted for the three conditions. Briefly interpret, in your own words, what it would mean if the F value for this sleep study was deemed statistically significant.
Do not copy or retype the example study scenario into your Assignment.
Note: Support your responses within your Assignment with evidence from the assigned Learning Resources. Provide a reference list for resources you used for this Assignment. Use APA style for in-text citations and references.