Question

Five students were tested before and after taking a class to improve their study habits. They were given articles to read which contained a known number of facts in each story. After the story each student listed as many facts as he/she could recall. The following data was recorded

Before	10	12	14	16	12
Atter	15	14	17	17	20

	a.	What is the alternative hypothesis?
	b.	What is the null hypothesis?
	c.	What is your conclusion, using á = 0.052 tail?
	d.	What type error may you be making because of your conclusion in part c?   Please show all work.
	e.	What is the size of effect, using Cohen’s d?

Answer 1

Ans:

Let d=After-Before

Before	10	12	14	16	12
Atter	15	14	17	17	20
d	5	2	3	1	8

a)

b)

Test statistic:

t=(3.8-0)/(2.775/SQRT(5))

t=3.062

df=5-1=4

p-value=tdist(3.062,4,1)=0.0188

c)Reject the null hypothesis,as p-value<0.052

There is sufficient evidence to conclude that students improved their study habits.

d)Type I error,as null hypothesis is rejected,which may be true in actual.

e)cohen'd=3.8/2.775=1.37