Question

QUESTION 1

1. A recent study showed that the hours a person exercised in a week affected the individual's resting heart rate. It was computed that r = -.93 and the least squares regression line was y = 82-1.25x, where x is the hours exercised and y is the resting heart rate. Which of the following is true?

   	A.	82 is the intercept and -1.25 is the slope. The slope of -1.25 means that for each additional hour exercised, one would predict a drop in resting heart rate of 1.25.
   	B.	-1.25 is the intercept and 82 is the slope. The slope of 82 meant that if a person excercised 1.25 hours per week, one would predict a resting heart rate of 82.
   	C.	82 is the intercept and -1.25 is the slope. The slope of -1.25 means that if a person excercised 1.25 hours per week, one would predict a resting heart rate of 82.
   	D.	82 is the intercept and -1.25 is the slope. The slope of -1.25 means that for each additional hour exercised, one would predict an increase in resting heart rate of 1.25.

1 points   

QUESTION 2

1. A recent study showed that the hours a person exercised in a week affected the individual's resting heart rate. It was computed that r = -.93 and the least squares regression line was y = 82-1.25x, where x is the hours exercised and y is the resting heart rate. Which of the following is true?

   	A.	Although the correlation of -.93 is very close to -1, one should not conclude that exercising causes a decrease in resting heart rate since there may be lurking variables.
   	B.	The correlation of -.93 is very close to -1, so one should conclude that exercising causes a decrease in resting heart rate.
   	C.	The correlation of -.93 is negative, so one should not conclude that exercising causes a decrease in resting heart rate.

1 points   

QUESTION 3

1. A recent study showed that the hours a person exercised in a week affected the individual's resting heart rate. It was computed that r = -.93 and the least squares regression line was y = 82-1.25x, where x is the hours exercised and y is the resting heart rate. A person exercises 8 hours per week. What resting heart rate is predicted by the regression line?

   	A.	82
   	B.	72
   	C.	83.25
   	D.	90

1 points   

QUESTION 4

1. Which of the following are true (more than one answer may be possible)?

   	A.	r is the slope of the regression line.
   	B.	The intercept of the regression line gives the predicted y value when the x value is 0.
   	C.	r has the same sign (positive or negative) as the slope of the regression line.
   	D.	One should create a scatterplot to verify that the linear model is appropriate.

1 points   

QUESTION 5

1. Which of the following are true(more than one answer may be possible)?

   	A.	Whenever including a lurking variable causes us to rethink the direction of an association, this is called Simpson's paradox.
   	B.	If r is very close to 1 or -1 it is ok to extrapolate the model to values outside the data set.
   	C.	In a study involving the association between playing video games and driving skills, age may be a lurking variable.
   	D.	If r is very close to 1 or -1 and there are no outliers and the scatterplot looks linear, one should conclude that the explanatory variable causes the change in the response variable.

Answer 1

Answer:

Answer to the question is as follows. Write back in case you've doubts:

Q1)

r = -.93

OLS, y = 82 - 1.25x

a. The 82 is intercept, -1.25 is the slope

B Is the right interpretation, please note the negative sign of 1.25 , which essentially means that for an additional hours per week there is a drop in resting heart rate of 1.25

Q2)

Correlation doesnt imply caustion. So, B is wrong. A is correct. C is also wrong, exercising may/may not cause a decrease in resting heart rate

Q3)

Thats' 82-1.25*8 = 72

B. 72 is correct

Q4)

A, B, and D is correct.

r is not the slope, although both have same direction of movement

Q5)

Yes, simpson' paradox happens when at some level of data the direction of association is different than the direction of relation at an overall level. A is correct

B. is not true. B can't be assumed for values outside the given rage

C is also true

D. We can't say that correlation implies causastion. D is not correct

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