a. ) In the first sheet, make your preliminary analysis, scatter the data, and check whether there is trend&seasonality. In a textbox, write your answer for trend and seasonality.

b. ) Depending on your decision on trend and seasonality, forecast 2021Q1 GDP with an appropriate method. Show and explain your work in the second sheet of your Excel file.

c.) Depending on your decision on trend and seasonality, forecast 2021Q1 GDP with an alternative appropriate method. Show and explain your work in the second sheet of your Excel file.

d.) In a new sheet, compare your two alternative forecast methods, based on MAD. Which one is better? Explain your choice, and state your final decision on the forecast for next period's GDP (the forecast with better method).

9 Period 10 Q1 1980 11 Q2 1980 12 Q3 1980 13 Q4 1980 14 Q1 1981 15 Q2 1981 16 Q3 1981 17 Q4 1981 Q1 1982 18 19 Q2 1982 20 Q3 1982 Quarter 3892 Q1 Q2 Q3 Q4 Q1 Q2 889288928892889288928892889288928 Q3 Q4 Q1 Q2 Q3 21 Q4 1982 22 Q1 1983 23 Q2 1983 24 Q3 1983 25 Q4 1983 26 Q1 1984 27 Q2 1984 28 Q3 1984 29 Q4 1984 30 Q11985 31 Q2 1985 32 Q3 1985 33 Q4 1985 34 Q11986 1986 35 Q2 36 Q3 1986 37 Q4 1986 38 Q1 1987 39 Q2 1987 40 Q3 1987 41 Q4 1987 Q4 42 Q1 1988 43 Q2 1988 44 Q3 1988 45 Q4 1988 46 Q1 1989 47 Q2 1989 Q2 48 Q3 1989 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q1 Q2 Q3 Q4 Q1 Q3 Year 1980 1980 1980 1980 1981 1981 1981 1981 1982 1982 1982 1982 1983 1983 1983 1983 1984 1984 1984 1984 1985 1985 1985 1985 1986 1986 1986 1986 1987 1987 1987 1987 1988 1988 1988 1988 1989 1989 1989 Dollars 74,144 77,602 86,282 84,720 84,538 89,420 99,242 95,158 91,630 94,040 103,417 99,094 96,806 101,460 113,010 110,040 107,443 112,075 122,679 119,789 116,619 120,368 132,712 130,328 124,766 127,948 138,805 135,111 133,185 139,745 151,421 149,985 148,063 153,318 163,615 161,898 158,215 164,436 176,561