GoldTrackers monitors the price of precious metals, and has daily data on prices and sales of gold for the past several years. One of their new MBA financial wizards has estimated the following relationship for gold sales in the past year of trading (250 observations):

Q = 4,000 - 0.01P + 1.5I - 1.25X + 2.0S R²= .96

(857)(0.002) (0.65)(0.44) (0.48)

where Q = daily sale of gold in ounces, P is the price of gold in dollars per ounce, I is the most recent one-month report on U.S. CPI inflation (in percent), X is an index of the exchange rate of the U.S. dollar compared to seven other currencies, and S is the market price of an ounce of silver in dollars. Standard errors are in parentheses.

a. Evaluate the results of this regression.

b. Recently, the price of gold has been $550 per ounce, inflation was measured at 0.4% for the month, the dollar has been trading at 89.9 on the foreign exchange index, and silver has been steady at $6 per ounce. What is the expected quantity of gold that will trade on a daily basis?

c. Are gold and silver substitutes or complements? Explain.