1. For a certain product it was found that annual sales volume could be well described by a third order autoregressive model. The estimated model obtained was: xt = 202 + 1.10xt-1 - 0.48xt-2 + 0.17xt-3 + εt
a. For 1993, 1994, and 1995, sales were 867, 923, and 951 respectively. Calculate sales, forecasts for the years 1996 through 1998.
b. Test the overall significance of the model, given that R2 = 0.7.
2. Consider the following time series data.
|
Period
|
|
|
1.1
|
150
|
|
1.2
|
284
|
|
1.3
|
119
|
|
1.4
|
115
|
|
2.1
|
187
|
|
2.2
|
266
|
|
2.3
|
138
|
|
2.4
|
116
|
|
3.1
|
170
|
|
3.2
|
221
|
|
3.3
|
124
|
|
3.4
|
121
|
a. Develop a centred 4- point moving average and a seasonal index for this time series.