Exercise: BMI and alcohol consumption in the 2005 questionnaire,6

Question 6: What are residuals? What can we conclude about their distribution?

Suggested answer

Residuals are the difference between the observed value of the outcome variable, BMI, and the value predicted from the predictor variable, alcohol consumption, using the regression equation.

Geometrically, they are the vertical distances from the point to the line, negative for points below the line and positive for points above the line.

Both the histogram and the Normal plot suggest that the distribution is positively skew, with a few extreme outliers at the high end.

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