Question

PSY-520 Graduate Statistics

Topic 7 – MANOVA Project

Directions: Use the following information to complete the assignment. While APA format is not required for the body of this assignment, solid academic writing is expected, and documentation of sources should be presented using APA formatting guidelines, which can be found in the APA Style Guide, located in the Student Success Center.

A researcher randomly assigns 33 subjects to one of three groups. Group 1 receives technical dietary information interactively from an on-line website. Group 2 receives the same information from a nurse practitioner, while Group 3 receives the information from a video tape made by the same nurse practitioner.

The researcher looked at three different ratings of the presentation; difficulty, usefulness, and importance to determine if there is a difference in the modes of presentation. In particular, the researcher is interested in whether the interactive website is superior because that is the most cost-effective way of delivering the information.

Group	Usefulness	Difficulty	Importance
1	20	5	18
1	25	9	8
1	23	15	20
1	16	9	22
1	20	6	22
1	28	14	8
1	20	6	13
1	25	8	13
1	24	10	24
1	18	10	20
1	17	9	4
2	28	7	14
2	25	14	5
2	26	9	20
2	19	15	22
2	29	14	12
2	15	6	2
2	29	10	5
2	26	11	1
2	22	5	2
2	15	15	14
2	29	6	4
2	15	6	3
3	22	8	12
3	27	9	14
3	21	10	7
3	17	9	1
3	16	7	12
3	19	9	7
3	23	10	1
3	27	9	5
3	23	9	6
3	16	14	22

1. Run the appropriate analysis of the data and interpret the results.
2. How could this study have been done differently? Why or why not would this approach be better?

Answer 1

One-way MANOVA using Minitab:

Procedure:

Step 1: Data Entering in Minitab

In Minitab, we set up the three variables. Under column C1 we entered the name of the independent variable, Group. Then, under column C2 we entered the name of the first dependent variable, Usefulness. Then, under column C3 we entered the name of the second dependent variable, Difficulty. Then, under column C4 we entered the name of the third idependent variable, Importance.The set up is as follows:

Group	Usefulness	Difficulty	Importance
1	20	5	18
1	25	9	8
1	23	15	20
1	16	9	22
1	20	6	22
1	28	14	8
1	20	6	13
1	25	8	13
1	24	10	24
1	18	10	20
1	17	9	4
2	28	7	14
2	25	14	5
2	26	9	20
2	19	15	22
2	29	14	12
2	15	6	2
2	29	10	5
2	26	11	1
2	22	5	2
2	15	15	14
2	29	6	4
2	15	6	3
3	22	8	12
3	27	9	14
3	21	10	7
3	17	9	1
3	16	7	12
3	19	9	7
3	23	10	1
3	27	9	5
3	23	9	6
3	16	14	22

Step 2:

Click Stat > ANOVA > General MANOVA... on the top menu. You will be presented with the General MANOVA dialogue box on the screen.

Step 3:

Transfer the dependent variables, Usefulness, Difficulty and Importance into the Responses: box. Transfer the independent variable, C1  Group, into the Model: box.

Step 4:

Click the OK button.

The Minitab output for the one-way MANOVA is shown below:

MANOVA for Group
s = 2 m = 0.0 n = 13.0

Criterion	Test Statistic	Degrees of Fredom			P
		F	Num	Denom
Wilks'	0.74289	1.495	6	56	0.197
Lawley-Hotelling	0.33522	1.509	6	54	0.193
Pillai's	0.2652	1.478	6	58	0.202
Roy's	0.29882

Step 5: Conclusion

There are three rows you can interpret to get the result of the one-way MANOVA. These are the Wilks', Lawley-Hotelling and Pillai's rows. We will use the results of the Wilks' row. This reports Wilks' Lambda (Λ) and its statistical significance. Wilks' Lambda statistic is found under the Test Statistics column. You can see that Wilks' Lambda is 0.7429. The statistical significance level (i.e., p-value) is found under the P column. You can see that it is .197 (i.e., p = .197). As such, the one-way MANOVA is not statistically significant (because p > .05).

In other words, there is a no any statistically significant difference between the modes of presentation.