Canadian retail sales in dollars for September 2006–August 2009 are shown in the graph. The horizontal axis represents the number of months since August 2006.

A linear regression analysis gives the following result:

The residual graph is:

a) What does the intercept represent?

b) What does the coefficient of months represent?

c) What is the forecast of the retail sales for October 2009?

d) What do you notice about the residuals?

e) Do you think the R² value for this regression is high or low?

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4.5E + 10 + 4E + 10 + 3.5E + 10 + 3E + 10 + 2.5E + 10 + 2E + 10 + 1.5E + 10 + - Series 1 1E + 10 + 5E + 09 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 Cofficients Standard Error 1.23E+09 57738651 t-Stat P-Value Intercept 33448518381 Months 55724727.16 27.30383 1.04E-24 0.96512 0.3413