Question 1

If a trend is given by yt = aebt, then:

Accepted Answer

A) the fitted trend value in period 0 is b. B) the trend is exponentially increasing. C) the trend is exponentially decreasing. D) the trend is increasing if b > 0 and decreasing if b < 0. A) the fitted trend value in period 0 is b. B) the trend is exponentially increasing. C) the trend is exponentially decreasing. D) the trend is increasing if b > 0 and decreasing if b < 0.

Question 2

Suppose the estimated quadratic model yt = 500 + 20t - t2 is the best-fitting trend of sales of XYZ Inc. using data for the past 20 years (t = 1, 2, …, 20). Which statement is incorrect?

Accepted Answer

A) Sales are increasing by about 20 units per year. 
B) The turning point would be in period 10. 
C) Latest year sales are no better than in year zero. 
D) The trend was higher in year 10 than in year 20. 
A) Sales are increasing by about 20 units per year. 
B) The turning point would be in period 10. 
C) Latest year sales are no better than in year zero. 
D) The trend was higher in year 10 than in year 20.

Question 3

Which is not a component of a time series?

Accepted Answer

A) Trend 
B) Seasonal 
C) Irregular 
D) Linearity 
A) Trend 
B) Seasonal 
C) Irregular 
D) Linearity

Question 4

The "up-and-down" component of a time series that represents periods of prosperity followed by recession over extended periods of time longer than one year is called:

Accepted Answer

A) trend variation. 
B) seasonal variation. 
C) cyclical variation. 
D) irregular variation. 
A) trend variation. 
B) seasonal variation. 
C) cyclical variation. 
D) irregular variation.

Question 5

The linear model's R2 may exceed the quadratic model's R2 fitted to the same data.

Accepted Answer

A) True 
 B)False

Question 6

If we fit a linear trend to data that are growing exponentially, which is least likely?

Accepted Answer

A) The fitted trend will be too low at the beginning and end. 
B) The fitted trend will be too high in the middle. 
C) The forecasts (if extrapolated) will be too low. 
D) The fit will be poor to the most recent data. 
A) The fitted trend will be too low at the beginning and end. 
B) The fitted trend will be too high in the middle. 
C) The forecasts (if extrapolated) will be too low. 
D) The fit will be poor to the most recent data.

Question 7

Which of the following measures of fit is expressed in percent?

Accepted Answer

A) SE (standard error) 
B) MAPE 
C) MSD 
D) MAD 
A) SE (standard error) 
B) MAPE 
C) MSD 
D) MAD

Question 8

An attraction of MAPE as a measure of fit is its simple interpretation.

Accepted Answer

A) True 
 B)False

Question 9

Cycles are usually ignored because there is no general theory to describe them.

Accepted Answer

A) True 
 B)False

Question 10

If a fitted trend equation is yt = 184e-.047t, then the forecast for period 4 is:

Accepted Answer

A) 195. 
B) 222. 
C) 152. 
D) 138. 
A) 195. 
B) 222. 
C) 152. 
D) 138.

Question 11

MegaStat's seasonal factor of 1.073 applied to a monthly trend forecast of 125.820 yields:

Accepted Answer

A) 135.005. 
B) 126.893. 
C) 137.044. 
D) 124.228. 
A) 135.005. 
B) 126.893. 
C) 137.044. 
D) 124.228.

Question 12

An exponential trend allows growth but cannot be used if the time series is declining.

Accepted Answer

A) True 
 B)False

Question 13

The exponential model would be attractive for analyzing a growing company's revenues over time.

Accepted Answer

A) True 
 B)False

Question 14

Using exponential smoothing, if Ft = 220, yt = 240, and α = .20, what is the new forecast Ft+1?

Accepted Answer

A) 217 
B) 224 
C) 232 
D) 243 
A) 217 
B) 224 
C) 232 
D) 243

Question 15

Which measure of fit is measured in the same units as Y?

Accepted Answer

A) MAPE 
B) MAD 
C) R2 
D) MSD 
A) MAPE 
B) MAD 
C) R2 
D) MSD

Question 16

Mary analyzed yard tractor sales from a suburban dealer over the last 15 years. She fitted several different trend models, shown below. Which trend model (if any) seems most reasonable for making forecasts for the next three years? What would Occam's Razor say?

Accepted Answer

Although the fourth-order polynomial giv

Question 17

The fitted annual sales trend is yt = 187e-.047t. The sales forecast for year 5 would be:

Accepted Answer

A) 236.9. 
B) 178.7. 
C) 175.3. 
D) 147.8. 
A) 236.9. 
B) 178.7. 
C) 175.3. 
D) 147.8.

Question 18

Bob analyzed water damage claims filed at a small Louisiana home insurance company over the last 15 years. He fitted several different trend models, shown below. Which trend model seems most reasonable (or more than one) for making forecasts for the next three years? What about the principle of Occam's Razor?

Accepted Answer

Although the fourth-order polynomial giv

Question 19

Which statement is most nearly correct regarding time-series trend models?

Accepted Answer

A) The quadratic model is best for a series that is growing by a constant percentage. 
B) A linear model may yield a higher R2 than a quadratic model. 
C) The exponential model is rarely used for financial data. 
D) The exponential model would be linear if we take the natural log of yt. 
A) The quadratic model is best for a series that is growing by a constant percentage. 
B) A linear model may yield a higher R2 than a quadratic model. 
C) The exponential model is rarely used for financial data. 
D) The exponential model would be linear if we take the natural log of yt.

Question 20

If Y1 = 216 and Y5 = 332, then the simple index number for period 5 is I5 = 153.7.

Accepted Answer

A) True 
 B)False

If a trend is given by y_t = ae^bt, then:

Suppose the estimated quadratic model y_t = 500 + 20t - t² is the best-fitting trend of sales of XYZ Inc. using data for the past 20 years (t = 1, 2, …, 20). Which statement is incorrect?

Which is not a component of a time series?

The "up-and-down" component of a time series that represents periods of prosperity followed by recession over extended periods of time longer than one year is called:

The linear model's R² may exceed the quadratic model's R² fitted to the same data.

If we fit a linear trend to data that are growing exponentially, which is least likely?

Which of the following measures of fit is expressed in percent?

An attraction of MAPE as a measure of fit is its simple interpretation.

Cycles are usually ignored because there is no general theory to describe them.

If a fitted trend equation is y_t = 184e^-.047^t, then the forecast for period 4 is:

MegaStat's seasonal factor of 1.073 applied to a monthly trend forecast of 125.820 yields:

An exponential trend allows growth but cannot be used if the time series is declining.

The exponential model would be attractive for analyzing a growing company's revenues over time.

Using exponential smoothing, if F_t = 220, y_t = 240, and α = .20, what is the new forecast F_t₊₁?

Which measure of fit is measured in the same units as Y?

Mary analyzed yard tractor sales from a suburban dealer over the last 15 years. She fitted several different trend models, shown below. Which trend model (if any) seems most reasonable for making forecasts for the next three years? What would Occam's Razor say?

The fitted annual sales trend is y_t = 187e^-.047^t. The sales forecast for year 5 would be:

Which statement is most nearly correct regarding time-series trend models?

If Y₁ = 216 and Y₅ = 332, then the simple index number for period 5 is I₅ = 153.7.

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Two-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

Exam 14: Time Series Analysis

If a trend is given by yt = aebt, then:

Suppose the estimated quadratic model yt = 500 + 20t - t2 is the best-fitting trend of sales of XYZ Inc. using data for the past 20 years (t = 1, 2, …, 20). Which statement is incorrect?

Which is not a component of a time series?

The "up-and-down" component of a time series that represents periods of prosperity followed by recession over extended periods of time longer than one year is called:

The linear model's R2 may exceed the quadratic model's R2 fitted to the same data.

If we fit a linear trend to data that are growing exponentially, which is least likely?

Which of the following measures of fit is expressed in percent?

An attraction of MAPE as a measure of fit is its simple interpretation.

Cycles are usually ignored because there is no general theory to describe them.

If a fitted trend equation is yt = 184e-.047t, then the forecast for period 4 is:

MegaStat's seasonal factor of 1.073 applied to a monthly trend forecast of 125.820 yields:

An exponential trend allows growth but cannot be used if the time series is declining.

The exponential model would be attractive for analyzing a growing company's revenues over time.

Using exponential smoothing, if Ft = 220, yt = 240, and α = .20, what is the new forecast Ft+1?

Which measure of fit is measured in the same units as Y?

Mary analyzed yard tractor sales from a suburban dealer over the last 15 years. She fitted several different trend models, shown below. Which trend model (if any) seems most reasonable for making forecasts for the next three years? What would Occam's Razor say?

The fitted annual sales trend is yt = 187e-.047t. The sales forecast for year 5 would be:

Which statement is most nearly correct regarding time-series trend models?

If Y1 = 216 and Y5 = 332, then the simple index number for period 5 is I5 = 153.7.

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Two-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

If a trend is given by y_t = ae^bt, then:

Suppose the estimated quadratic model y_t = 500 + 20t - t² is the best-fitting trend of sales of XYZ Inc. using data for the past 20 years (t = 1, 2, …, 20). Which statement is incorrect?

The linear model's R² may exceed the quadratic model's R² fitted to the same data.

If a fitted trend equation is y_t = 184e^-.047^t, then the forecast for period 4 is:

Using exponential smoothing, if F_t = 220, y_t = 240, and α = .20, what is the new forecast F_t₊₁?

The fitted annual sales trend is y_t = 187e^-.047^t. The sales forecast for year 5 would be:

If Y₁ = 216 and Y₅ = 332, then the simple index number for period 5 is I₅ = 153.7.