13: Time-Series Analysis-LOS n习题精选 2010, particular, justify, monthly

土豆妮

Session 3: Quantitative Methods: Quantitative
Methods for Valuation
Reading 13: Time-Series Analysis

LOS n: Select and justify the choice of a particular time-series model from a group of models

 

 

 

Alexis Popov, CFA, is analyzing monthly data. Popov has estimated the model x_t = b₀ + b₁ × x_t-1 + b₂ × x_t-2 + e_t. The researcher finds that the residuals have a significant ARCH process. The best solution to this is to:

A) re-estimate the model using only an AR(1) specification.

B) re-estimate the model using a seasonal lag.

C) re-estimate the model with generalized least squares.

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wendyshure

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luqian55

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luqian55

 

[此贴子已经被作者于2010-5-30 18:13:03编辑过]

土豆妮

Alexis Popov, CFA, wants to estimate how sales have grown from one quarter to the next on average. The most direct way for Popov to estimate this would be:

A) an AR(1) model.

B) an AR(1) model with a seasonal lag.

C) a linear trend model.

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If the goal is to simply estimate the dollar change from one period to the next, the most direct way is to estimate x_t = b₀ + b₁ × (Trend) + e_t, where Trend is simply 1, 2, 3, ....T. The model predicts a change by the value b₁ from one period to the next.

土豆妮

Alexis Popov, CFA, is analyzing monthly data. Popov has estimated the model x_t = b₀ + b₁ × x_t-1 + b₂ × x_t-2 + e_t. The researcher finds that the residuals have a significant ARCH process. The best solution to this is to:

A) re-estimate the model using only an AR(1) specification.

B) re-estimate the model using a seasonal lag.

C) re-estimate the model with generalized least squares.

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If the residuals have an ARCH process, then the correct remedy is generalized least squares which will allow Popov to better interpret the results.

土豆妮

Alexis Popov, CFA, has estimated the following specification: x_t = b₀ + b₁ × x_t-1 + e_t. Which of the following would most likely lead Popov to want to change the model’s specification?

A) Correlation(et, et-2) is significantly different from zero.

B) Correlation(et, et-1) is not significantly different from zero.

C) b0 < 0.

土豆妮

Alexis Popov, CFA, has estimated the following specification: x_t = b₀ + b₁ × x_t-1 + e_t. Which of the following would most likely lead Popov to want to change the model’s specification?

A) Correlation(et, et-2) is significantly different from zero.

B) Correlation(et, et-1) is not significantly different from zero.

C) b0 < 0.

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If correlation(e_t, e_t-2) is not zero, then the model suffers from 2^nd order serial correlation. Popov may wish to try an AR(2) model. Both of the other conditions are acceptable in an AR(1) model.

土豆妮

Alexis Popov, CFA, wants to estimate how sales have grown from one quarter to the next on average. The most direct way for Popov to estimate this would be:

A) an AR(1) model.

B) an AR(1) model with a seasonal lag.

C) a linear trend model.