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Exercise: Head circumference and height, answer 11

Question 11: What assumptions are required for this test?
Do you think they are met here?
What further information would you like to assess this?

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Suggested answer

We assume that the deviations from the line in the outcome variable,
i.e. the differences between the observed head circumferences and
those predicted by the regression line,
follow a Normal distribution whose variance is uniform,
that is, it is unrelated to the magnitude of the predictor variable, height.

We would like a plot of the distribution of the residuals, such as a histogram,
and a scatter plot of residuals against height or against the value predicted
by the regression:

d

d

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