(For students with access to statistical software or spreadsheet programs.) Consider the fol lowing data for a cross-section of individuals in the population, in which Q = Quantity (in 100s) of aspirin purchased in a year P = Average price of aspirin in that year Y = Annual income A = Age of buyer Observation Q P Y A 1 1 1.5 20 25 2 2 1.5 40 20 3 4 1 12 25 4 2 1 10 30 5 2 1 8 30 6 3 2 30 35 7 3.5 1.5 30 40 8 4 2 20 40 9 7 1 20 45 10 1 3 15 40 11 2 2 18 30 12 3 2 20 32 Observation Q P Y A 13 3.5 2 15 36 14 4 2 10 30 15 2 3 25 20 16 1 4 15 25 17 8 2 15 55 18 9 1 40 50 19 1 4 10 45 20 10 1.5 30 55 21 6 1.5 35 60 22 2 1 30 40 23 3 1 25 40 24 3 2 20 35 25 3 2 15 35 26 4 3 20 35 27 1 4 20 25 28 1 4 25 30 29 2 5 28 30 30 3 1 30 32