Question

. A simple linear model to compare the progression of boys and girls in thee above data has the form SprintTime = a*Sex + b*Sex*Age, where Sex represents dummy variables Boy and Girl. This model represents separate straight lines for boys and girls, similar to the figure in the lecture showing the relationship between change scores and pre-test value in a control and experimental group.

In the model above, we might want to answer the question: what is the difference in mean sprint time between boys and girls? Suppose there was a difference in the mean age of the boys and girls in this sample. (There is always a difference, even if it's trivial!) What are the two names of the means (they mean the same thing) that allow you to answer the question, taking into account (adjusting for) the difference in mean age?

Answer 1

Sorint li The regression equation is that ou Sprint Time = at Sentbt Sexy Age.. Sen = 1.7 of 4 Sex = bays and Sex=o in sen gists. anestopper Then T Sprint Time = attb*1 * Age = atbaage, if Sex=1 1 s iq Sex = 0, , Therefore, the difference between boys and girls in mean spoint time is atba Age.