In: Statistics and Probability
18 ) Use the following linear regression equation to answer the questions.
x1 = 1.8 + 3.1x2 –
7.6x3 + 1.5x4
(b) Which number is the constant term? List the coefficients with
their corresponding explanatory variables.
constant | |
x2 coefficient | |
x3 coefficient | |
x4 coefficient |
(c) If x2 = 9, x3 = 10, and
x4 = 5, what is the predicted value for
x1? (Use 1 decimal place.)
d) Suppose x3 and x4 were
held at fixed but arbitrary values and x2
increased by 1 unit. What would be the corresponding change in
x1?
Suppose x2 increased by 2 units. What would be
the expected change in x1?
Suppose x2 decreased by 4 units. What would be
the expected change in x1?
(e) Suppose that n = 9 data points were used to construct
the given regression equation and that the standard error for the
coefficient of x2 is 0.335. Construct a 90%
confidence interval for the coefficient of x2.
(Use 2 decimal places.)
lower limit | |
upper limit |
(f) Using the information of part (e) and level of significance 1%,
test the claim that the coefficient of x2 is
different from zero. (Use 2 decimal places.)
t | |
t critical ± |