Q6. Using Equation ONE, what is the sales forecast for the second quarter of the next year?

A)   $56.02 million.

B)   $51.09 million.

C)   $46.31 million.

Q7. Which of the coefficients that appear in both equations are not significant at the 5% level in a two-tailed test?

A)   The coefficient on Q2 only.

B)   The coefficients on Q1 and Q2 only.

C)   The intercept only.

Q8. Conditional heteroskedasticity is a problem for:

A)   Equation ONE but not Equation TWO.

B)   both Equations ONE and TWO.

C)   neither equation.

Q9. Mercado probably did not include a fourth dummy variable Q4, which would have had 0, 0, 0, 1 as its first four observations because:

A)   the intercept is essentially the dummy for the fourth quarter.

B)   it would have lowered the explanatory power of the equation.

C)   it would not have been significant.

Q10. If Mercado determines that Equation TWO is the appropriate specification, then he is essentially saying that for each year, value of sales from quarter three to four is expected to:

A)   remain approximately the same.

B)   grow, but by less than $1,000,000.

C)   grow by more than $1,000,000.

[此贴子已经被作者于2009-1-8 14:16:06编辑过]

答案和详解如下：

Q6. Using Equation ONE, what is the sales forecast for the second quarter of the next year?

A)   $56.02 million.

B)   $51.09 million.

C)   $46.31 million.

Correct answer is B)

The estimate for the second quarter of the following year would be (in millions):

31.4083 + (−2.4631) + (24 + 2) × 0.851786 = 51.091666.

Q7. Which of the coefficients that appear in both equations are not significant at the 5% level in a two-tailed test?

A)   The coefficient on Q2 only.

B)   The coefficients on Q1 and Q2 only.

C)   The intercept only.

Correct answer is A)

The absolute value of the critical T-statistics for Equation ONE and TWO are 2.093 and 2.086, respectively. Since, the t-statistics for Q2 in Equations ONE and TWO are −1.6685 and −1.9188, respectively, these fall below the critical values for both equations.

Q8. Conditional heteroskedasticity is a problem for:

A)   Equation ONE but not Equation TWO.

B)   both Equations ONE and TWO.

C)   neither equation.

Correct answer is C)

Mercado would use the Breusch-Pagan test for heteroskedasticity. Mercado regressed the squared residuals from each equation on the respective independent variables. The R² values were 0.008801 and 0.006313 respectively. The test-statistic for the Breusch-Pagan test is n × (R²) which is distributed as a Chi-squared statistic with degrees of freedom equal to the number of independent variables. Assuming a 5% level of significance, the respective critical values are 7.815 and 9.488. The respective test statistic values are 24 × 0.008801 = 0.2112 and 24 × 0.006313 = 0.1515. Both computed test statistics are much less than their respective critical values; thus, Mercado would conclude that conditional heteroskedasticity is not a problem.

Q9. Mercado probably did not include a fourth dummy variable Q4, which would have had 0, 0, 0, 1 as its first four observations because:

A)   the intercept is essentially the dummy for the fourth quarter.

B)   it would have lowered the explanatory power of the equation.

C)   it would not have been significant.

Correct answer is A)

The fourth quarter serves as the base quarter, and for the fourth quarter, Q1 = Q2 = Q3 = 0. Had the equation included a Q4 as specified, we could not have had an intercept. In that case, for Equation ONE for example, the estimate of Q4 would have been 31.40833. The dummies for the other quarters would be the 31.40833 plus the estimated dummies from Equation ONE. In an equation that included Q1, Q2, Q3, and Q4 but no intercept, for example:

Q1 = 31.40833 + (−3.77798) = 27.63035

Such an equation would produce the same estimated values for the dependent variable.

Q10. If Mercado determines that Equation TWO is the appropriate specification, then he is essentially saying that for each year, value of sales from quarter three to four is expected to:

A)   remain approximately the same.

B)   grow, but by less than $1,000,000.

C)   grow by more than $1,000,000.

Correct answer is B)

The specification of Equation TWO essentially assumes there is no difference attributed to the change of the season from the third to fourth quarter. However, the time trend is significant. The trend effect for moving from one season to the next is the coefficient on TREND times $1,000,000 which is $852,182 for Equation TWO.