Suppose
that Case i is an outlier in the sense that an amount δ is added to
its expected value. Let u i be the unit vector with 1 in the ith
position and zeros elsewhere and write the revised model is y = Xβ
+ δu i + e. Weisberg (1985) calls this the mean shift outlier
model. Using standard methodology, develop the test statistic for
the hypothesis, H 0 : δ = 0 and show that the resulting
t-statistic, with n − m− 2 degrees of freedom, is equivalent to the
Studentized residual. Hint: Use the ideas developed in the
discussion of added-variable plots to show that ˆ δ = r i(i) and
that the residual sum of squares is given by RSS (i)
Suppose that Case i is an outlier in the sense that an amount δ is added to its expected value. Let u i be the unit vector with 1 in the ith position and zeros elsewhere and write the revised model is...
Suppose that Case i is an outlier in the sense that an amount 8 is added to its expected value. Let ui be the unit vector with 1 in the ith position and zeros elsewhere and write the revised model is Weisberg (1985) calls this the mean shift outlier model. Using standard methodology, develop the test statistic for the hypothesis, Ho: 8 -0 and show that the resulting t-statistic, with n - m- 2 degrees of freedom, is equivalent to...