Answer these questions using correct grammar and English:
- What do you think that Analysis of Variance means? Where does the name come from?
- Discuss the ways in which one-way ANOVA might be useful in your own research.
- What would be some cautions in using one-way ANOVA?
Do the problem below using Excel.
Computation Help for Excel:
1. Enter data into data table.
2. Go to TOOLS > DATA ANALYSIS (PC) or STATISTICS > ANALYSIS OF VARIANCE (ANOVA) (MAC)
3. Select "ANOVA simple"
4. Enter input range-this will be all of your data (you can simply draw a box around your data table)
5. Check how the data is grouped-probably by columns
6. Check the box that says "labels in first row" if your columns are headed with anything (e.g. A1 says "age" and A2-30 has your participants' ages)
7. Set alpha (it's preset to .05)
8. Set output-where do you want your data to go? It can either go on the same sheet, on a different sheet, or in a whole new workbook.
9. Hit "OK"
10. If you find significance for the overall ANOVA, you must run a series of t tests to find between which groups there are significant differences.
One-way ANOVA-
A research study was conducted to examine the clinical efficacy of a new antidepressant. Depressed patients were randomly assigned to one of three groups: a placebo group, a group that received a low dose of the drug, and a group that received a moderate dose of the drug. After four weeks of treatment, the patients completed the Beck Depression Inventory. The higher the score, the more depressed the patient. The data are presented below.
|
Placebo
|
Low Dose
|
Moderate Dose
|
|
38
|
22
|
14
|
|
47
|
19
|
26
|
|
39
|
8
|
11
|
|
25
|
23
|
18
|
|
42
|
31
|
5
|
Perform a one-way ANOVA on the data provided. You can either use the One-way ANOVA calculator that I provided or you can perform the analysis in Excel. Once the analysis is performed, respond to the questions below:
1. What is your computed answer?
2. What would be the null hypothesis in this study?
3. What would be the alternate hypothesis?
4. What are the independent variables in this study?
5. What is the dependent variable in this study?
6. Is there a significant difference among the groups?
7. If there is a significant difference, where specifically are the differences?
8. Interpret your answer.
9. Create an ANOVA table using your findings.