Question

4. In a "Before and After" study, you wish to determine whether a protein rich diet has any effect on the weight of German Shepherds. You weigh several dogs at your kennel at the beginning of the study, and then weigh these same dogs again after two months. Given the following data (and assuming the dogs in your convenience sample are representative of all German Shepherds), do you believe there is a difference in the average weight for German Shepherds after one month on this diet? Test at the a = 0.05 level of significance. Weight (in pounds) BEFORE Weight (in pounds) AFTER 74 80 68 74 71 7 7 6 6 68 74 85

Answer 1

Ans:

Paired t test:

	before	after	d
1	74	80	6
2	68	74	6
3	71	77	6
4	66	68	2
5	74	85	11
		d-bar	6.2
		sd	3.194

Test statistic:

t=(6.2-0)/(3.194/sqrt(5))

t=4.34

df=5-1=4

p-value(2 tailed)=tdist(4.34,4,2)=0.0123

As,p-value<0.05,we reject the null hypothesis.

There is sufficient evidence to conclude that there is significant difference in the average weight for German Shepherds after one month on this diet.