Question

An eccentric professor believes that a child with iq 100 should have a reading test score of 50, and that reading score should increase by 1 point for every additional point of iq. what is the equation of the professor’s regression line for predicting reading score from iq?

Answer 1

y=x-50 where y is the reading test score and and x is iq score. This can be found intuitively. Since each point in IQ should increase the score by one point, we know the slope should be 1. Then we use the fact that reading test score is just iq shifted down by 50. This leads to the subtraction of 50.