Stats 2 test 2

Which measure is better to assess the practical significance of a multiple regression model? Select one: a. Standard error b. F test c. Adjusted R squared d. p-value

Adjusted R Squared

A fitted multiple regression equation is Y = 12 + 3X1 - 5X2 + 7X3 + 2X4. When X1 increases 2 units and X2 increases 2 units as well, while X3 and X4 remain unchanged, what change would you expect in your estimate of Y? Select one: a. Increase by 2 b. No change in Y c. Decrease by 2 d. Decrease by 4

Decrease by 4

A binary (categorical) predictor should not be used along with nonbinary predictors. Select one: True False

False

A high variance inflation factor (VIF) indicates a significant predictor in the regression. Select one: True False

False

Heteroscedasticity exists when all the errors (residuals) have the same variance. Select one: True False

False

Which of the following graphical methods is used to assess the assumption of normally distributed residuals? a. Time series plot b. Scatter plot c. Histogram d. Dot plot

Histogram

The relationship of Y to four other variables was established as Y = 12 + 3X1 - 5X2 + 7X3 + 2X4. When X1 increases 5 units and X2 increases 3 units, while X3 and X4 remain unchanged, what change would you expect in your estimate of Y? Select one: a. No change b. Decrease by 15 c. Increase by 15 d. Increase by 5

No change

Which of the following graphical methods is used to assess the assumption of independent residuals? Select one: a. Time series plot b. Histogram c. Scatter plot d. Dot plot

Time Series Plot

A disadvantage of Excel's Data Analysis regression tool is that it expects the independent variables to be in a block of contiguous columns so you must delete a column if you want to eliminate a predictor from the model. Select one: True False

True

If R2 = .36 in the model Sales = 268 + 7.37 Ads, then Ads explains 36 percent of the variation in Sales.

True

Which is indicative of an inverse relationship between X and Y? Select one: a. A negative correlation coefficient b. A negative p-value for the correlation coefficient c. Either a negative F statistic or a negative p-value d. A negative F statistic

a. A negative correlation coefficient

In a time-series plot, we can assume that residuals are independent if Select one: a. Number of times the graph crosses the x-axis is equal to n/2 b. Number of times the graph crosses the x-axis is less than n/2 c. Number of times the graph crosses the x-axis is greater than n/2 d. None of the given options is true

a. Number of times the graph crosses the x-axis is equal to n/2

Simple regression analysis means that: Select one: a. we have only one explanatory variable. b. there are only two independent variables. c. the data are presented in a simple and clear way. d. we have only a few observations.

a. we have only one explanatory variable.

In simple regression, when testing the significance of slope, if we reject the null hypothesis then a. Can't tell from given information b. We conclude that the independent variable is a significant predictor of dependent variable c. We conclude that the dependent variable is a significant predictor of independent variable d. We conclude that the independent variable is not a significant predictor of dependent variable

b. We conclude that the independent variable is a significant predictor of dependent variable

In multiple regression models, multicollinearity occurs: Select one: a. When residuals are not normally distributed b. When the independent variables are related to each other Correct c. When residuals are heteroscedastic d. When the independent variables are not related to each other

b. When the independent variables are related to each other

The sample coefficient of correlation does not have which property? Select one: a. It is tested for significance using a t-test. b. It is also sometimes called Pearson's r. c. It assumes that Y is the dependent variable. Correct d. It can range from -1.00 up to +1.00.

c. It assumes that Y is the dependent variable.

If a categorical variable has 5 categories, we include: a. One indicator variables in the regression model b. Five indicator variables in the regression model c. Six indicator variables in the regression model d. Four indicator variables in the regression model

d. Four indicator variables in the regression model

Which is not true of the coefficient of determination? Select one: a. It reports the percent of the variation in Y explained by X. b. It is calculated using sums of squares (e.g., SSR, SSE, SST). c. It is the square of the coefficient of correlation. d. It is negative when there is an inverse relationship between X and Y.

d. It is negative when there is an inverse relationship between X and Y.

A fitted multiple regression equation is Y = 28 + 5X1 - 4X2 + 7X3 + 2X4. When X1 increases 2 units and X2 increases 2 units as well, while X3 and X4 remain unchanged, what change would you expect in your estimate of Y? Select one: a. Increase by 4 b. Increase by 2 c. No change in Y d. Decrease by 4

increase by 2

The variable used to predict another variable is called the: Select one: a. dependent variable. b. independent variable. c. response variable. d. regression variable.

independent variable