The following table reports both the seasonal indexes for all national park visitors and the number of visitors to the Addo National Park, near Port Elizabeth, on a quarterly basis (in 1 000s) for 2008, 2009 and 2010.
|
Season
|
Seasonal indexes
|
2008
|
2009
|
2010
|
|
Summer
|
112
|
196
|
199
|
214
|
|
Autumn
|
94
|
147
|
152
|
163
|
|
Winter
|
88
|
124
|
132
|
145
|
|
Spring
|
106
|
177
|
190
|
198
|
Assume that the seasonal pattern of visitors to the Addo National Park follows the national profile of visitors to all national parks.
(a) Remove the influence of seasonal factors on the number of visitors to the Addo National Park for each of the periods from 2008 to 2010.
(b) Plot both the original data series and the de-seasonalised data series of the number of visitors to the Addo National Park over the three-year period on the same axis.
(c) Is any significant trend evident from the de-seasonalised data? Comment.
(d) Use Excel's Line with Marker option in the Insert > Chart tab to plot the data in (b).