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Author Question: A public health researcher wants to use regression to predict the sun safety knowledge of pre-school ... (Read 60 times)

sheilaspns

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Question 1

Suppose that the following model was fit to a set of data.

     E(y) = β0 + β1x1 + β2x2

The corresponding plot if residuals against predicted values is shown. Interpret the plot.


◦ It appears that the variance of ε is not constant.
◦ It appears that a quadratic model would be a better fit.
◦ The residuals appear to be randomly scattered so that no model modifications are necessary.
◦ It appears that the data contain an outlier.

Question 2

A public health researcher wants to use regression to predict the sun safety knowledge of pre-school children.  The researcher randomly sampled 35 preschoolers, assigned them to one of two groups, and then measured the following three variables:

SUNSCORE: y = Score on sun-safety comprehension test
READING: x1 = Reading comprehension score
GROUP: x2 = 1 if child received a Be Sun Safe demonstration, 0 if not

A regression model was fit and the following residual plot was observed.



Which of the following assumptions appears violated based on this plot?
◦ The mean of the errors is zero
◦ The errors are normally distributed
◦ The variance of the errors is constant
◦ The errors are independent


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Marked as best answer by sheilaspns on Feb 14, 2020

wergv

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sheilaspns

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Reply 2 on: Feb 14, 2020
Thanks for the timely response, appreciate it


LVPMS

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Reply 3 on: Yesterday
Excellent

 

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