Question

Background: Anorexia is well known to be difficult to treat. The data set provided below contains data on the weight gain for three groups of young female anorexia patients. These groups include a control group, a group receiving cognitive behavioral therapy and a group receiving family therapy. Source: Hand, D. J., Daly, F., McConway, K., Lunn, D. and Ostrowski, E. eds (1993) A Handbook of Small Data Sets. Chapman & Hall, Data set 285 (p. 229).

Directions: Click on the Data button below to display the data. Copy the data into a statistical software package and click the Data button a second time to hide it. Then perform an analysis of variance (ANOVA) to determine whether or not the differences in weight gain between the treatment groups is statistically significant.

Data

Control	CBT	Family
-0.5	1.7	11.4
-9.3	0.7	11
-5.4	-0.1	5.5
12.3	-0.7	9.4
-2	-3.5	13.6
-10.2	14.9	-2.9
-12.2	3.5	-0.1
11.6	17.1	7.4
-7.1	-7.6	21.5
6.2	1.6	-5.3
-0.2	11.7	-3.8
-9.2	6.1	13.4
8.3	1.1	13.1
3.3	-4	9
11.3	20.9	3.9
0	-9.1	5.7
-1	2.1	10.7
-10.6	-1.4
-4.6	1.4
-6.7	-0.3
2.8	-3.7
0.3	-0.8
1.8	2.4
3.7	12.6
15.9	1.9
-10.2	3.9
	0.1
	15.4
	-0.7

1. State the null and alternative hypotheses.
   
   
   
2. Compute the test statistic. Document how SSTr and SSE were computed. Use 4 decimal places for the sample means, sample standard deviations and the grand mean and round your answers for SSTr and SSE to 2 decimal places.
   
   Use the values for SSTr and SSE to complete the following ANOVA table. Round each of your answers to 2 decimal places.
   

   Source	S.S.	df	M.S.	F
   Treatment
   Error
   Total

3. Compute the p-value. Provide the name of the distribution and the parameters used to compute the p-value. Then enter your answer rounded to 4 decimal places.
   
   
   
4. Interpret the results of the significance test. Is this result statistically significant? Is this result important from a practical perspective?
   

Answer 1