超星 - 随堂测试9-2

单选题

By including another variable in the regression, you will

A. decrease the regression R2 if that variable is important.
B. eliminate the possibility of omitted variable bias from excluding that variable.
C. look at the t-statistic of the coefficient of that variable and include the variable only if the coefficient is statistically significant at the 1% level.
D. decrease the variance of the estimator of the coefficients of interest.

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单选题

Errors-in-variables bias

A. is present when the probability limit of the OLS estimator is given by <img>.
B. arises when an independent variable is measured imprecisely.
C. arises when the dependent variable is measured imprecisely.
D. always occurs in economics since economic data is never precisely measured.

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单选题

Sample selection bias

A. occurs when a selection process influences the availability of data and that process is related to the dependent variable.
B. is only important for finite sample results.
C. results in the OLS estimator being biased, although it is still consistent.
D. is more important for nonlinear least squares estimation than for OLS.

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单选题

Simultaneous causality bias

A. is also called sample selection bias.
B. happens in complicated systems of equations called block recursive systems.
C. results in biased estimators if there is heteroskedasticity in the error term.
D. arises in a regression of Y on X when, in addition to the causal link of interest from X to Y, there is a causal link from Y to X.

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单选题

Panel data estimation can sometimes be used

A. to avoid the problems associated with misspecified functional forms.
B. in case the sum of residuals is not zero.
C. in the case of omitted variable bias when data on the omitted variable is not available.
D. to counter sample selection bias.

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单选题

Misspecification of functional form of the regression function

A. is overcome by adding the squares of all explanatory variables.
B. is more serious in the case of homoskedasticity-only standard error.
C. results in a type of omitted variable bias.
D. requires alternative estimation methods such as maximum likelihood.

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单选题

Errors-in-variables bias

A. is only a problem in small samples.
B. arises from error in the measurement of the independent variable.
C. becomes larger as the variance in the explanatory variable increases relative to the error variance.
D. is particularly severe when the source is an error in the measurement of the dependent variable.

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单选题

A survey of earnings contains an unusually high fraction of individuals who state their weekly earnings in 100s, such as 300, 400, 500, etc. This is an example of

A. errors-in-variables bias.
B. sample selection bias.
C. simultaneous causality bias.
D. companies that typically bargain with workers in 100s of dollars.

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单选题

In the case of errors-in-variables bias,

A. maximum likelihood estimation must be used.
B. the OLS estimator is consistent if the variance in the unobservable variable is relatively large compared to variance in the measurement error.
C. the OLS estimator is consistent, but no longer unbiased in small samples.
D. binary variables should not be used as independent variables.

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单选题

Sample selection bias occurs when

A. the choice between two samples is made by the researcher.
B. data are collected from a population by simple random sampling.
C. samples are chosen to be small rather than large.
D. the availability of the data is influenced by a selection process that is related to the value of the dependent variable.

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