Homework Sourse18 Use the following sales data to compute a trend and seaso
18) Use the following sales data to compute a trend- and seasonally-adjusted forecast for quarter 3 of year 7. Round off seasonal indexes to two decimals.
Use the following sales data to compute a trend- and seasonally-adjusted forecast for quarter 3 of year 7. Round off seasonal indexes to two decimals.
Year
Quarter
2008
2009
2010
2011
2012
2013
1
86.4
95.3
93.5
99.1
103.4
113.4
2
93
102.7
100.9
103
108.6
113.5
3
91.9
98.6
99.4
101.2
109.5
113.2
4
107.3
107.9
113.7
115.6
122.3
127.1
| Year | ||||||
| Quarter | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 |
| 1 | 86.4 | 95.3 | 93.5 | 99.1 | 103.4 | 113.4 |
| 2 | 93 | 102.7 | 100.9 | 103 | 108.6 | 113.5 |
| 3 | 91.9 | 98.6 | 99.4 | 101.2 | 109.5 | 113.2 |
| 4 | 107.3 | 107.9 | 113.7 | 115.6 | 122.3 | 127.1 |
Solution
Computation for Seasonal Fluctuation :
Computation for Seasonal Indexes
| Qtr. | Sales | 3-Qtr. Moving Total | 3-Qtr. Moving Average |
| 2008 1 | 86.4 | ||
| 2 | 93 | 271.3 | 90.43 |
| 3 | 91.9 | 292.2 | 97.40 |
| 4 | 107.3 | 294.5 | 98.17 |
| 2009 1 | 95.3 | 305.3 | 101.77 |
| 2 | 102.7 | 296.6 | 98.87 |
| 3 | 98.6 | 309.2 | 103.07 |
| 4 | 107.9 | 300 | 100.00 |
| 2010 1 | 93.5 | 302.3 | 100.77 |
| 2 | 100.9 | 293.8 | 97.93 |
| 3 | 99.4 | 314 | 104.67 |
| 4 | 113.7 | 312.2 | 104.07 |
| 2011 1 | 99.1 | 315.8 | 105.27 |
| 2 | 103 | 303.3 | 101.10 |
| 3 | 101.2 | 319.8 | 106.60 |
| 4 | 115.6 | 320.2 | 106.73 |
| 2012 1 | 103.4 | 327.6 | 109.20 |
| 2 | 108.6 | 321.5 | 107.17 |
| 3 | 109.5 | 340.4 | 113.47 |
| 4 | 122.3 | 345.2 | 115.07 |
| 2013 1 | 113.4 | 349.2 | 116.40 |
| 2 | 113.5 | 340.1 | 113.37 |
| 3 | 113.2 | 353.8 | 117.93 |
| 4 | 127.1 |
