Here I'm expecting the specific reason to which model (additive/multiplicative) should we use? how to decide? and what is the exact reason behind it. Also if possible could you please explain how to identify the model based on given data.

Thank you.

Q 2(c) [15 Marks] The time series data in Table Q2 shows Quarterly Sales Data (in thousands) from 1979-81. Generate a graph of the data explaining what kind of model should be used to decompose the data and provide reasons for your choice. Calculate the Trend (using 2X4pt Moving Averages), Seasonal Index and Seasonally-Adjusted data. Graph the Trend and Seasonally-Adjusted data (but not the Seasonal Index data). Year Quarter 1 1979 1979 Sales 72 110 2 1979 3 117 1979 4 172 1980 1 76 1980 2 112 1980 3 130 1980 4 194 1981 1 78 1981 2 119 1981 3 128 1981 4 201 81 1982 1 1982 2 134 1982 3 141 1982 4 216 Table Q2 [End of Question 2] Q 2(c) [15 Marks] The time series data in Table Q2 shows Quarterly Sales Data (in thousands) from 1979-81. Generate a graph of the data explaining what kind of model should be used to decompose the data and provide reasons for your choice. Calculate the Trend (using 2X4pt Moving Averages), Seasonal Index and Seasonally-Adjusted data. Graph the Trend and Seasonally-Adjusted data (but not the Seasonal Index data). Year Quarter 1 1979 1979 Sales 72 110 2 1979 3 117 1979 4 172 1980 1 76 1980 2 112 1980 3 130 1980 4 194 1981 1 78 1981 2 119 1981 3 128 1981 4 201 81 1982 1 1982 2 134 1982 3 141 1982 4 216 Table Q2 [End of Question 2]