4.5The data in the following table show the daily sales of pa- perback books and hardcover books at the same store. The task is to forecast the next four days’ sales for paperbacks and hardcover books.
(a)Use single exponential smoothing and compute the mea- sures of forecasting accuracy over the test periods 11–30.
(b)Repeat using the method of linear exponential smoothing (Holt’s method).
(c)Compare the error statistics and discuss the merits of the two forecasting methods for these data sets.
(d)Compare the forecasts for the two methods and discuss their relative merits.
(e)Study the autocorrelation functions for the forecast er- rors resulting from the two methods applied to the two data series. Is there any noticeable pattern left in the data?
Day
Paperbacks
Hardcovers
1
199
139
16
243
240
2
172
128
17
225
189
3
111
18
167
222
4
209
19
237
158
5
161
191
20
202
178
6
119
168
21
186
217
7
195
170
22
176
261
8
145
23
232
238
9
131
184
24
10
183
135
25
190
214
11
143
218
26
182
200
12
141
198
27
201
13
230
28
283
14
29
188
220
15
155
206
30
247
259
Already registered? Login
Not Account? Sign up
Enter your email address to reset your password
Back to Login? Click here