exam 2 pp

Question 1

theoretical meaning of “95% confident”

Answer 1

in repeating sampling, 95% of all similarly constructed intervals will contain the true slope of the line

Question 2

extrapolation

Answer 2

if you try to predict for an x outside the sample range

Question 3

x value chosen for 95 % prediction/confidence…

Answer 3

since the value of x is with the range of the sample, the interval is valid.

Question 4

assumptions required for regression (icon)

Answer 4

independent errors
constant variance of errors
mean = 0 for errors
normally distributed errors

Question 5

dummy variables

Answer 5

E(y) = B0 + B1x1 where x1 = { 1 if ____, 0 if ____}

Question 6

R^2

Answer 6

after adjusting for sample size and number of independent variable, approximately 38% of sample variation in ___ can be explained by the model.

want high to use in practice

Question 7

SD

Answer 7

about 95% of the actual ___ values will fall within 2s ___ of their predicted values

want low to use in practice

Question 8

PI and CI

Answer 8

PI is always wider than a CI and a 95% is always wider than a 90%

Question 9

interaction

Answer 9

label axes with y (height) and x1 (long)

non-parallel lines labeled with 2 values of x2

___

test is B3 and Ha: not equal to 0
Must use p-value on B3 specifically

there is sufficient/ insufficient evidence to conclude that the relationship between ___ and ___ depends on ___.

Question 10

curvature test

Answer 10

B2

must use p-value on B2 specifically

there is sufficient/ insufficient evidence to conclude that curvature exist between ___ and ___.