Question

1.Investigators studied the relationship between screen time (measured in hours/week) and body-mass-index, BMI=wt/ht^2

(wt=weight in kg and ht=height in meters), in men age 25 -45 . They surveyed 6234 U.S. men in this age group, the scatter diagram for the data was homoscedastic and the BMI data was approximately normally distributed both unconditionally and in each vertical strip.

The investigators generated the following summary statistics:

X=35 SDX=12

Y=27 SDY=6 r=0.8

where X=hours of screen-time per week, and Y=BMI.

(a) (2 pts) Find the regression equation for predicting BMI from hours of screen time.

(b) (2 pts) According to this regression, by how much does BMI increase on average for each additional hour of weekly screen time?

(c) (2 pts) It appears from this study that decreasing weekly consumption of screen time will lower BMI. Does this conclusion follow from the data provided here? Answer yes or no and explain your choice.

Answer #1

Investigators studied the relationship between screen time
(measured in hours/week) and body- mass-index, BMI= wt/ht2 (wt =
weight in kg and ht = height in meters), in men age 25 - 45 . They
surveyed 6234 U.S. men in this age group, the scatter diagram for
the data was homoscedastic and the BMI data was approximately
normally distributed both unconditionally and in each vertical
strip.
The investigators generated the following summary
statistics:
X=35 SDX=12
Y = 27 SDY = 6...

1. For a pair of sample x- and y-values, what is the difference
between the observed value of y and the predicted value of y? a) An
outlier b) The explanatory variable c) A residual d) The response
variable
2. Which of the following statements is false:
a) The correlation coefficient is unitless. b) A correlation
coefficient of 0.62 suggests a stronger correlation than a
correlation coefficient of -0.82. c) The correlation coefficient,
r, is always between -1 and 1....

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