1. A major amusement park has the following num- ber of visitors each quarter from 2005 through 2009:
a. Construct the four-quarter centered moving average for these data and determine the percentages of the moving average for the quarters.
b. Determine the seasonal indexes for the quarters.
c. Use the seasonal indexes to deseasonalize the original time series.
2. Given the degree-day data of Exercise 18.11,
(a) determine the monthly seasonal indexes for January through December, then (b) use these indexes to deseasonalize the original time series.
3. Given the data of Exercise 18.13, (a) determine the monthly seasonal indexes for January through December, then
(b) use these indexes to deseasonalize the original time series.
4. A mail-order firm has found the following sea- sonal indexes for the number of calls received each month. Below the seasonal indexes is the actual number of calls (thousands) per month during 2009.
a. Using the seasonal indexes, deseasonalize the data for 2009.
b. The president of the firm is quite pleased that the number of calls went up each month during the May through December portion of 2009. Based on the results obtained in part (a), is the firm's performance really on the increase?
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Month:
|
J
|
F
|
M
|
A
|
M
|
J
|
J
|
A
|
S
|
O
|
N
|
D
|
|
Seasonal index:
|
110
|
105
|
90
|
60
|
70
|
75
|
85
|
95
|
100
|
105
|
140
|
165
|
|
Calls in 2009:
|
7.2
|
5.9
|
5.5
|
3.2
|
4.0
|
4.1
|
5.3
|
5.4
|
5.7
|
6.1
|
7.9
|
8.2
|