If we wish to use a regression line to determine the effect of multiple treatment levels , why can't we just plot the average outcome for each treatment level and "connect the dots?"
A) Connecting the dots generally will not form a line.
B) Using averages for each treatment level will generally create bias.
C) This will cause us to have too few equations to solve for our unknown parameters.
D) We cannot use a regression line to measure the effects of multiple treatments.

Question

Quizplus · Accepted Answer

Connecting the dots formed by plotting the average outcome for each treatment level does not guarantee a linear relationship, which is a fundamental assumption in linear regression analysis. This method oversimplifies the data and ignores the variability within each treatment level, potentially leading to incorrect conclusions about the relationship between variables.

If We Wish to Use a Regression Line to Determine