3-Now consider the following estimates for the model above (standard errors are

Question

3-Now consider the following estimates for the model above (standard errors are in for each regression parameter) cGPA,-1.4 (0.25) + 0.412 (0.25) * hsGPA-0.75(0.06) * phone, + ui. cGPA is college GPA hsGPA is high school GPA phone is using your phone in class (per hour) a-What is the predicted value of college GPA for a student who had a 4.0 high school GPA and uses the phone for 30 minutes per class? b-Interpret phone (the coefficient on phone) c-Is the coefficient on phone statistically significant at the 95% confidence level? Explain e-Can you reject the hypothesis Ho: GPA-0 at the 95% confidence level?

Explanation / Answer

a)when hsGPA = 4

phone = 30 min = 0.5 hour

cGPA^ = 1.4 + 0.412 * 4 - 0.75 * 0.5

= 2.673

b) b2 = -0.75

it means that those whose use phone more by 1 hour has lower cGPA by 0.75 on average

c)

t = -0.75/0.06

= -12.5

clearly |TS| > critical value

hence the variable phone is significant

d) since you have not provided sample size (n)

degree of freedom = n -k-1 = n-2-1 = n-3

t* for 95% confidence interval

P(t >t*) = 0.025

confidence interval will be

(-0.75 - t * 0.06 , -0.75 + t *0.06)

you just to plug the values of t in it , t is around 2 , if sample size is more than 3

Comment n ,i will complete , or find t yourself using critical tables or excel, R , etc

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