Question

1. Use the following table to calculate the correlation coefficient (r).

            and Interpret the results in words.

Credibility X	Persuasion Y
59	64
54	60
59	63
58	72
71	78
55	69
55	69
54	67

2.Explain Type I error

Answer 1

Ans:

1)

	Credibility(x)	Persuasion (y)	xy	x^2	y^2
1	59	64	3776	3481	4096
2	54	60	3240	2916	3600
3	59	63	3717	3481	3969
4	58	72	4176	3364	5184
5	71	78	5538	5041	6084
6	55	69	3795	3025	4761
7	55	69	3795	3025	4761
8	54	67	3618	2916	4489
Total=	465	542	31655	27249	36944

Correlation cofficient,r=(8*31655-465*542)/SQRT((8*27249-465^2)*(8*36944-542^2))

r=0.681

There is positive correlation between credibility and prsuasion.

2)Type I error:

When the null hypothesis is true and you reject it, you make a type I error. The probability of making a type I error is ?, which is the level of significance you set for your hypothesis test.

An ? of 0.05 indicates that you are willing to accept a 5% chance that you are wrong when you reject the null hypothesis. To lower this risk, you must use a lower value for ?. However, using a lower value for alpha means that you will be less likely to detect a true difference if one really exists.