12.64 The following model was fitted to observations from 1972 to 1979 in an attempt to explain oil-pricing behavior:

yn = 37x1 + 5.22x2 10.0292 10.502 where yn = difference between price in the current year and price in the previous year, in dollars per barrel x1 = difference between spot price in the current year and spot price in the previous year x2 = dummy variable taking the value 1 in 1974 and 0 otherwise to represent the specific effect of the oil embargo of that year The numbers in parentheses under the coefficients are the estimated coefficient standard errors.

Interpret verbally and graphically the estimated coefficient on the dummy variable.