Harvey Enterprises, Inc., has hired you to analyze demand for Product Z. A statistical analysis of demand for the past 30 months shows (standard errors in parentheses):
QZ = 500 - 8PZ + 5PX + 0.05A + 0.025Y
(350) (2.5) (2) (0.03) (0.011)
R2 = 0.93
Standard Error of the Estimate = 20
Here, QZ is market demand for Product Z, PZ is the price of Z in dollars, A is dollars of advertising expenditures, PX is the average price in dollars of another (unidentified) product, and Y is dollars of household income. At present, the price of Z is $500, PX is $600, advertising expenditures are $10,000, and average per capita income is $40,000.
Which of the variables above is NOT statistically significant at the 0.05 level?