Question

Part II. Researchers are testing the effects of a new diet program on n = 10 healthy participants. One topic that researchers are interested in are overall attitudes towards dieting. They are interested in knowing if the new diet program will change the participants attitudes towards dieting. Participants rated their attitude about diets before and after the diet program.

Participant	Before Diet	After Diet
1 2 3 4 5 6 7 8 9 10	15 10 7 18 5 9 12 13 15 9	10 13 12 8 14 14 21 17 22 13

1. The first thing you must do is determine which t – test you need to run. Once you have made that decision, you can proceed to answer b-d

2. Using symbols, state the null and alternative hypothesis

c) Is there significant difference between the two groups? Calculate Cohens D and report the value (this calculation will be done manually) Is the effect size that you calculated small, medium, or large?

4. Report the confidence interval from the SPSS output. Interpret the confidence interval. You may use the slides from last lecture as a reference.

d. Create a figure

Answer 1

Result:

SPSS used.

The first thing you must do is determine which t – test you need to run. Once you have made that decision, you can proceed to answer b-d

Since data are paired, paired test used to compare.

Using symbols, state the null and alternative hypothesis

d = difference( before-after)

Ho: µd=0 H1: µd ≠ 0

Is there significant difference between the two groups? Calculate Cohens D and report the value (this calculation will be done manually) Is the effect size that you calculated small, medium, or large?

Paired Samples Statistics
	Mean	N	Std. Deviation	Std. Error Mean
Pair 1	before	11.3000	10	4.02906	1.27410
after	14.4000	10	4.45222	1.40791

Paired Samples Test
	Paired Differences	t	df	Sig. (2-tailed)
Mean	Std. Deviation	Std. Error Mean	95% Confidence Interval of the Difference
Lower	Upper
Pair 1	before - after	-3.10000	6.06355	1.91746	-7.43760	1.23760	-1.617	9	0.140

Calculated t=-1.617, P=0.140 which is > 0.05 level of significance. Ho is not rejected. we conclude that there is no significant difference between before and after diet.

Cohens D = 3.1/6.0636 =0.5112

The effect size is medium.

Report the confidence interval from the SPSS output. Interpret the confidence interval. You may use the slides from last lecture as a reference.

95% CI for the mean difference of before and after is (-7.4376, 1.2376).

d. Create a figure