In a study to compare the effectiveness of treatments for ADHD in children, 40 children diagnosed with ADHD were randomly assigned to one of four conditions: (1) nutritional intervention without drugs (NI); (2) behavioral intervention without drugs (BI); nutritional intervention and a prescription drug (DM-D); behavioral intervention and a prescription drug (BI-D). At the end of three months, participants' hyperactivity and attention levels were measured. Participants' scores on the attention measure are given below. Higher scores indicate higher (better) attention levels. I have put the data into an SPSS file in the Assignments folder on HuskyCT.
|
NI
|
BI
|
NI-D
|
BI-D
|
|
17
13
18
19
23
16
17
20
23
21
|
16
15
12
18
17
18
13
17
16
15
|
17
21
20
19
16
17
15
12
16
18
|
19
25
22
21
19
21
23
16
20
19
|
(a) Which of the following statistical analyses could be used to analyze the data? Circle your answer for each.
One-way ANOVA: YES NO
Two-way ANOVA: YES NO
Repeated Measures: YES NO
(b) Test the assumption of homogeneity of variances and state your conclusion, indicating how you reached it. Report the relevant statistic and p-value.
(c) The researchers wanted to answer the following questions:
1. Does the use of a prescription drug increase mean attention levels in ADHD children, averaging over other interventions?
2. Is a nutritional intervention more effective than a behavioral intervention in increasing mean attention levels, averaging over drug conditions?
3. Does the addition of a prescription drug to a nutritional intervention have the same effect on mean attention levels as the addition of the drug to a behavioral intervention?
Carry out an appropriate analysis in SPSS and answer these questions.
(d) Construct all pairwise contrasts using a Tukey procedure and report only those that are statistically significant at the .05 level (you do not have to do these by hand!). State what the contrast is, and report the estimate, standard error used in constructing the CI, and the 95% confidence interval. State clearly what conclusion you would draw based on the results.