. Sometimes it is believed that β0 is 0 because we think that E(Y |X = 0) = 0. Then the appropriate model is  yi = β1Xi + i.  This model is usually called “regression through the origin” since the...

. Sometimes it is believed that β0 is 0 because we think that E(Y |X = 0) = 0. Then the appropriate model is

 yi = β1Xi +
i.

 This model is usually called “regression through the origin” since the regression line is forced through the origin. The least-squares estimator of β1 minimizes