1: Explain the term ‘autoregression’ in a time series regression
context.
2. Explain the term ‘autocorrelation’ and the problems it
creates when using OLS regression in time series data.
Use alpha= 0.05 to test the following time series for positive
autocorrelation.
Period Sales
1 2
2 5
3 9
4 6
5 6
6 9
7 10
8 12
9 10
10 13
11 18
12 11
13 13
14 13
15 14
a) Determine the Durbin-Watson statistic.
(Round to two decimal places as needed.)
b) Identify the critical values.
dL=
dU=
(Round to two decimal places as needed.)
Explain what is meant by the following time series terms
i) Sample autocorrelation function
ii) The if and only if conditions for the stationarity of the
ARMA(p,q) process
iii) The partial autocorrelation function
5. Use a=0.05 to test the following time series for positive
autocorrelation.
Period Sales
1 4
2 7
3 11
4 10
5 10
6 11
7 14
8 16
9 12
10 13
11 19
12 12
13 14
14 16
15 15
a. Determine the Durbin-Watson statistic. (Round to two
decimal places as needed.)
b. Identify the critical values. dL=?
dU=?(Round to two decimal places as needed.)
5. Use a=0.05 to test the following time series for positive
autocorrelation.
Period Sales
1 4
2 7
3 11
4 10
5 10
6 11
7 14
8 16
9 12
10 13
11 19
12 12
13 14
14 16
15 15
a. Determine the Durbin-Watson statistic. (Round to two
decimal places as needed.)
b. Identify the critical values. dL=? dU=?
(Round to two decimal places as needed.)
Please explain what the term collinearity (or multicollinearity
in the multiple regression context) means. Does it affect our
regression estimates (i.e., betas) or their variances? If so,
please explain how? Does multicollinearity affect the chances of
making either a Type I or Type II error? If so, how
so?
2. Consider the same model in a time series context, namely, yt
= β0 + β1xt + ut, t = 1, . . . , T where ut = ρut−1 + vt, |ρ| <
1, vt is i.i.d. with E(vt) = 0 and Var(vt) = σ 2 v . (a) What is
the problem in using OLS to estimate the model? Is there any
problem in hypothesis testing? (b) Show that Cov(ut, ut−τ ) = ρ
τVar(ut−τ ) for τ...
Explain what is meant by autocorrelation of regression residuals
and detail what estimation problems it causes. How could you detect
and solve the residual autocorrelation problem?