Exam 14: Advanced Ols

arrow
  • Select Tags
search iconSearch Question
flashcardsStudy Flashcards
  • Select Tags

Suppose we omit X2 from the following in a bivariate model Yi = β\beta 0 + β\beta 1X1i + ε\varepsilon i And suppose X2 is negatively related to X1 and β\beta 2 is positive, while β\beta 1 is positive. What is the likely effect of omitting X2 on our estimate of β\beta 1?

Free
(Multiple Choice)
4.8/5
(39)
Correct Answer:
Verified

C

Suppose we omit X3 (a variable that does not affect Y) from the following in a bivariate model Yi = β\beta 0 + β\beta 1X1i + β\beta 2X2i + ε\varepsilon i And suppose each of the independent variables are correlated with the other independent variables. What is the consequence of omitting X3 on β\beta 1hat?

Free
(Multiple Choice)
4.9/5
(36)
Correct Answer:
Verified

A

Suppose we omit X3 (a variable that actually affects Y) from the following in a bivariate model Yi = β\beta 0 + β\beta 1X1i + β\beta 2X2i + ε\varepsilon i And suppose each of the independent variables are correlated with the other independent variables. What is the consequence of omitting X3 on β\beta 1hat?

Free
(Multiple Choice)
4.9/5
(39)
Correct Answer:
Verified

C

Even if we don't observe a variable, we can make informed speculations about the effect of omitting the variable on coefficients on variables we do observe.

(True/False)
4.8/5
(43)

Please explain, in words and using equations, why B1hat is a random variable.

(Essay)
4.8/5
(31)

Which assumption is necessary for the expected value of b1hat to equal b1?

(Multiple Choice)
4.8/5
(39)

The conditions for omitted variable bias can be derived by substituting the true value of Y into the B1hat equation for the model where X2 is omitted.

(True/False)
4.9/5
(33)

If the errors are not homoscedastic and uncorrelated with each other, then OLS estimates are biased and but the easy-to-use standard OLS equation for the variance of B1hat is still appropriate.

(True/False)
4.9/5
(38)

Which assumption is not necessary for the following equation to correctly characterize the standard error of β\beta 1hat?

(Multiple Choice)
4.7/5
(29)

We derive the B1hat equation by setting the sum of squared residuals equation to 0 and solving for B1hat.

(True/False)
4.9/5
(43)

Derive the equation for attenuation bias due to a measurement error in the independent variable in a case where there is only one independent variable.

(Essay)
4.7/5
(37)

9. Suppose that X1 is measured with error. Yi = β\beta 0 + β\beta 1X1i + ε\varepsilon i Xi = X*1i + ν\nu i In which of the following cases will the bias be most severe?

(Multiple Choice)
4.9/5
(35)

In which of the following will omitted variable bias be the most severe? Treat X2 as the omitted variable in a bivariate model of Yi = β\beta 0 + β\beta 1X1i + ε\varepsilon i

(Multiple Choice)
4.9/5
(42)

Suppose we omit X2 from the following in a bivariate model Yi = β\beta 0 + β\beta 1X1i + ε\varepsilon i And suppose X2 is positively related to X1 and β\beta 2 is positive, while β\beta 1 is negative. What is the likely effect of omitting X2 on our estimate of β\beta 1?

(Multiple Choice)
4.8/5
(35)

Derive the equation for the omitted variable bias condition.

(Essay)
4.8/5
(40)

A single poorly measured independent variable will not cause other coefficients to be biased.

(True/False)
4.7/5
(40)

Since a lot of times we do not have the values for X2, and X2 could be correlated both with X1 and Y, we will have to anticipate the sign of the bias, but we won't necessarily know the magnitude of the bias. Provide a list/table that gives the anticipated sign of the bias based on the relationship between X2 and X1 as well as the relationship between X2 and Y.

(Essay)
4.8/5
(39)

10. Suppose that X1 is measured with error. Yi = β\beta 0 + β\beta 1X1i + ε\varepsilon i Xi = X*1i + ε\varepsilon i Which of the following is most accurate?

(Multiple Choice)
4.9/5
(34)

Show the steps in involved in deriving the OLS estimates for B1hat, and describe the assumption that is necessary for B1hat to be an unbiased estimator of B1.

(Essay)
4.8/5
(43)

Suppose we omit X3 from the following in a bivariate model Yi = β\beta 0 + β\beta 1X1i + β\beta 2X2i + ε\varepsilon i And suppose each of the independent variables is completely uncorrelated with the other independent variables (i.e., they have been randomly chosen in a randomized experiment). What is the consequence of omitting X3 on β\beta 1hat?

(Multiple Choice)
4.8/5
(33)
close modal

Filters

  • Essay(0)
  • Multiple Choice(0)
  • Short Answer(0)
  • True False(0)
  • Matching(0)