chpt 14 review

Question 1

With simple linear regression how many variables do we use

Answer 1

1 dependent and 1 independent variable

Question 2

in simple linear regression what doe we use to appropximate the realtionship

Answer 2

a straight line

Question 3

what is the line type to calculate slope and intercept

Answer 3

see sheet

Question 4

what is the formula for slope

Answer 4

see sheet

Question 5

what is the formula for intercept

Answer 5

see sheet

Question 6

what is the line type to use for calculating SST/SSR/SSE/ R2/ and rxy

Answer 6

see sheet

Question 7

What is the formula for r 2 (coefficent of determination)

Answer 7

SSR/SST

Question 8

what does the coefficient of determination tell us

Answer 8

% of variation that can be explained by the ….. the gregression equation?

Question 9

WHat are some importing things about the coefficent of determination

Answer 9

1. cannot be negative

2. larger values imply that the observations are more closely gropued around the lease squares line

Question 10

what is the formula for rxy (correlation coefficent)

Answer 10

sqaure root of r2

Question 11

what does correlation coefficent tell us

Answer 11

strength of association b/w x and y

values are b/w 1 and -1

• values are positive or negative dependent on the slop (is it positive or negative)

Question 12

Testing for significance for simple linear regression what is the null and alternative hypothesis

Answer 12

Ho: B1 = 0
Ha: B1 does not equal 0

NOTE: two tailed test

Question 13

What are the rules for a two tailed test for a t-test

Answer 13

if positive, double the p-value

Question 14

When testing for significance for simple linear regression what kind of tests can we use

Answer 14

t- test and F- test

Question 15

In simple linear regression when you reject the t-test or the F- test what can you conclude

Answer 15

Reject Ho: conclude that a statistically significant relationship exists

Do Not reject Ho: not significant, conclude that no statistical evidence a significant relationship exists

Question 16

How do you calculate the t-test for simple linear regression

Answer 16

t= bi/ sbi

Question 17

How do you calculate sbi

Answer 17

1. MSE = sse/n-2
2. s = square root of MSE
3. sbi = s/ sqaure root of sum (xi-xbar) square

Question 18

what are the degrees of freedom for t test in simple linear regression

Answer 18

n-2

Question 19

What is the formula for the F test in simple linear regression and what is the d-f

Answer 19

MSR/MSE

df - is what the df is for MSR and MSE

MSR df =
MSE df =

Question 20

What is the confidence interval for simple linear regression

Answer 20

if 0 is included in the ibterval then …..

calculation: bi +/- ta/2sbi

Question 21

in simple linear regression are the t-test and F-test provide the same result?

Answer 21

yes

Question 22

For confidence and prediction intervals they are more precise when

Answer 22

the value of the independent value X* is closer to Xbar

Question 23

which interval is wider confidence or prediction

Answer 23

prediction interval

Question 24

What is the confidence interval used for

Answer 24

estimate of the MEAN value of Y for a given value of x

Question 25

What is the prediction interval used for

Answer 25

used to predict the value of the dep. var y for a NEW observation

Question 26

What do you use to MEASURE of how well the estimated regression line FITS the data

Answer 26

R2

Coefficient of Determination

Question 27

What test do we use to test whether B1 is significant

Answer 27

t-test bi/sbi