1. A firm predicts it will use 560,000 gallons of water next year. If the seasonal index of water consump- tion is 135 for the second quarter of the year, what is the forecast for water consumption during that quarter?
2. The quarterly seasonal indexes for a firm's elec- tricity consumption are 115, 92, 81, and 112 for quarters I-IV. It has been forecast that electricity consumption will be 850,000 kilowatt-hours during 2014. Forecast electricity consumption for each quarter of 2014.
3. When autocorrelation of the residuals is present, what effect can this have on interval estimation and significance tests regarding the regression model involved?
4. What is the Durbin-Watson test for autocorrela- tion, and how can it be useful in evaluating the relevance autocorrelation of the residuals at the 0.05 level of signifi- cance. Comment on the appropriateness of using this model for this set of data.
t yt t yt t yt
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of a given regression model that has been fitted to a set
of time series data?
|
1
|
97.0
|
6
|
125.5
|
11
|
150.6
|
|
|
2
|
109.7
|
7
|
132.9
|
12
|
157.8
|
|
18.44 The least-squares regression equation yˆ 5 98.1 1 5.0t
|
3
|
110.3
|
8
|
139.7
|
13
|
158.3
|
|
has been fitted to the shipment data given here. Calculate
|
4
|
121.5
|
9
|
145.6
|
14
|
166.9
|
|
the Durbin-Watson d statistic and test for positive
|
5
|
130.4
|
10
|
149.4
|
15
|
175.8
|