Dr. Blum conducts a study examining the relationship between health behaviors and anxiety in elementary school children. She predicts that physical activity is very important, but that other factors need to be considered such as sleep and screen time. Below are the results of her multivariable regression. Coefficients
Unstandardized Standardized Coefficients
Coefficients
Model B Std. Error Beta 1 Sig
1 Constant 29.743 1.329 22.384 .000
StepsPerDay -001 .000 -.465 -5.649 .000
SleepPerNight -.011 .032 -.020 -.338 .736
ScreenPerDay .041 .112 .029 .368 .713
a Dependent Variable: Anxiety
1. What is the Intercept in Dr. Blum's regression results? Use the regression table above.
a. 29.743.
b. 0.041.
c. 1.329.
d. 22.384.
2. In the regression table, why would Dr. Blum would report standardized beta coefficients when he publishes his results?
A. Standardized beta coefficients are in the original units.
B. Standardized beta coefficients indicate statistical significance.
C. Standardized beta coefficients allow comparing relative strengths of predictors in the model
D. Standardized beta coefficients indicate % of variance explained by combined effects of predictor variables.
3. Dr. Blum finds that his analysis produced R2-.37. What does this mean?
A. His measures have a significant effect.
B. 37% of his predictors are significant.
C. His measures are not valid.
D. 37% of the variability in Anxiety can be explained by his predictors.
4. Why are Dr. Blum's results from the multivariable regression more convincing than the results from her Pearson correlation table?
a. because she is able to test her prediction about physical activity (StepsPerDay) while taking into consideration the relationship of physical activity with sleep and screen time.
b. they are not more convincing, because StepsPerDay is not a statistically significant predictor of Anxiety in the multivariable regression (p>.01).
c. they are not more convincing, because the relationship is stronger in the correlation table
d. because using regression she can claim a causal relationship between StepsPerDay and Anxiety.
5. What are the units for Pearson's r for the association between StepsperDay and Anxiety?
a. standard deviations.
b. r does not have units.
c. whatever units the data were originally measured in, squared.
d. whatever units the data were originally measured in.
6. In Dr. Blum's regression table, when all the variables are entered into a multivariable linear regression, using an alpha Type-1 error rate of p<.05, what variable is the strongest predictor of Anxiety?
A. StepsPerDay.
B. ScreenPer Day.
C. SleepPer Night.
D. SleepPerNight and ScreenPer Day have the same strength (p>.01).
7. Which of the following is the accurate interpretation for StepsPerDay unstandardized beta value? Use the regression table above.
A. For 1 standard deviation increase in Anxiety, the expected increase in StepsPerDay is -.001
B. For 1 unit of increase in StepsPerDay, the expected increase in Anxiety is --001.
C. For 1 standard deviation increase in StepsPerDay, the expected increase in Anxiety is -.001
D. For 1 unit increase in Anxiety, the expected increase in StepsPerDay is -001.