Deck 14: Regression and Forecasting Models

Question 1

Winter's method is an exponential smoothing method,which is appropriate for a series with trend but no seasonality.

Answer 1

False

Question 2

The least squares line is the line that minimizes the sum of the residuals.

Answer 2

False

Question 3

The adjusted R² is used primarily to monitor whether extra explanatory variables really belong in a multiple regression model.

Answer 3

True

Question 4

Which of the following is not one of the commonly used summary measures for forecast errors?

A) MAE (mean absolute error)
B) MFE (mean forecast error)
C) RMSE (root mean square error)
D) MAPE (mean absolute percentage error)

Question 5

When using the moving average method,you must select ____ which represent(s)the number of terms in the moving average.

A) a smoothing constant
B) the explanatory variables
C) an alpha value
D) a span

Question 6

A time series can consist of four different components: trend,seasonal,cyclical,and random (or noise).

Question 7

In regression analysis,the variable we are trying to explain or predict is called the

A) independent variable
B) dependent variable
C) regression variable
D) statistical variable

Question 8

A "fan" shape in a scatterplot indicates:

A) nonconstant error variance
B) a nonlinear relationship
C) the absence of outliers
D) sampling error

Question 9

A useful graph in almost any regression analysis is a scatterplot of residuals (on the vertical axis)versus fitted values (on the horizontal axis),where a "good" fit not only has small residuals,but it has residuals scattered randomly around zero with no apparent pattern.

Question 10

In regression analysis,we can often use the standard error of estimate s_e to judge which of several potential regression equations is the most useful.

Question 11

Forecasting models can be divided into three groups.They are:

A) time series,optimization,and simulation methods
B) judgmental,regression,and extrapolation methods
C) judgmental,random,and linear methods
D) linear,non-linear,and extrapolation methods

Question 12

In multiple regression,the coefficients reflect the expected change in:

A) Y when the associated X value increases by one unit
B) X when the associated Y value increases by one unit
C) Y when the associated X value decreases by one unit
D) X when the associated Y value decreases by one unit

Question 13

In reference to the equation ,the value 0.10 is the expected change in Y per unit change in X.

Question 14

The smoothing constant used in simple exponential smoothing is analogous to the span in moving averages.

Question 15

An important condition when interpreting the coefficient for a particular independent variable X in a multiple regression equation is that:

A) the dependent variable will remain constant
B) the dependent variable will be allowed to vary
C) all of the other independent variables remain constant
D) all of the other independent variables be allowed to vary

Question 16

Winters' model differs from Holt's model and simple exponential smoothing in that it includes an index for:

A) seasonality
B) trend
C) residuals
D) cyclical fluctuations

Question 17

The adjusted R² adjusts R² for:

A) non-linearity
B) outliers
C) low correlation
D) the number of explanatory variables in a multiple regression model

Question 18

The term autocorrelation refers to:

A) the analyzed data refers to itself
B) the sample is related too closely to the population
C) the data are in a loop (values repeat themselves)
D) time series variables are usually related to their own past values

Question 19

The residual is defined as the difference between the actual and predicted,or fitted values of the response variable.

Question 20

The percentage of variation explained R² is the square of the correlation between the observed Y values and the fitted Y values.

Question 21

Exhibit 14-3
The quarterly numbers of applications for home mortgage loans at a branch office of a large bank are recorded in the table below.
Refer to Exhibit 14-3.Obtain a simple exponential smoothing forecast again,this time optimizing the smoothing constant.Does it make much of an improvement?

Question 22

Exhibit 14-3
The quarterly numbers of applications for home mortgage loans at a branch office of a large bank are recorded in the table below.
Refer to Exhibit 14-3.Use a moving average model to forecast these data,requesting 4 quarters of future forecasts.Use a span of 4 quarters.

Question 23

Exhibit 14-2
The station manager of a local television station is interested in predicting the amount of television (in hours)that people will watch in the viewing area.The explanatory variables are: X₁ age (in years),X₂ education (highest level obtained,in years)and X₃ family size (number of family members in household).The multiple regression output is shown below:

Refer to Exhibit 14-2.Use the information above to estimate the linear regression model.

Question 24

Exhibit 14-1
An express delivery service company recently conducted a study to investigate the relationship between the cost of shipping a package (Y),the package weight in pounds (X₁),and the distance shipped in miles (X₂).Twenty packages were randomly selected from among the large number received for shipment,and a detailed analysis of the shipping cost was conducted for each package.The sample information is shown in the table below:
Refer to Exhibit 14-1.How does the R² value for this multiple regression model compare to that of the simple regression model estimated above? Interpret the adjusted R² values for the two models.

Question 25

Exhibit 14-2
The station manager of a local television station is interested in predicting the amount of television (in hours)that people will watch in the viewing area.The explanatory variables are: X₁ age (in years),X₂ education (highest level obtained,in years)and X₃ family size (number of family members in household).The multiple regression output is shown below:

Refer to Exhibit 14-2.Interpret each of the estimated regression coefficients of the regression model above.

Question 26

Exhibit 14-1
An express delivery service company recently conducted a study to investigate the relationship between the cost of shipping a package (Y),the package weight in pounds (X₁),and the distance shipped in miles (X₂).Twenty packages were randomly selected from among the large number received for shipment,and a detailed analysis of the shipping cost was conducted for each package.The sample information is shown in the table below:
Refer to Exhibit 14-1.Estimate a simple linear regression model involving shipping cost and package weight.Interpret the slope coefficient of the least squares line as well as R².

Question 27

Exhibit 14-1
An express delivery service company recently conducted a study to investigate the relationship between the cost of shipping a package (Y),the package weight in pounds (X₁),and the distance shipped in miles (X₂).Twenty packages were randomly selected from among the large number received for shipment,and a detailed analysis of the shipping cost was conducted for each package.The sample information is shown in the table below:
Refer to Exhibit 14-1.Add the second explanatory variable (distance shipped)to the regression model.Estimate and interpret this expanded model.

Question 28

Exhibit 14-2
The station manager of a local television station is interested in predicting the amount of television (in hours)that people will watch in the viewing area.The explanatory variables are: X₁ age (in years),X₂ education (highest level obtained,in years)and X₃ family size (number of family members in household).The multiple regression output is shown below:

Refer to Exhibit 14-2.Identify and interpret the percentage of variation explained (R²)for the model.

Question 29

Exhibit 14-3
The quarterly numbers of applications for home mortgage loans at a branch office of a large bank are recorded in the table below.
Refer to Exhibit 14-3.Use simple exponential smoothing to forecast these data,requesting 4 quarters of future forecasts.Use the default smoothing constant of 0.10.Is this better than the moving average model?

Question 30

Exhibit 14-3
The quarterly numbers of applications for home mortgage loans at a branch office of a large bank are recorded in the table below.
Refer to Exhibit 14-3.Obtain a time series chart.Which of the forecasting models do you think should be used for forecasting based on this chart? Why?