search for: w_ii

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2005 Feb 11
1
cook's distance in weighted regression
...k's distance in weighted linear regression. In this case cook's distance should be given not as in OLS case by h_ii*r_i^2/(1-hii)^2 divided by k*s^2 (1) (where r is plain unadjusted residual, k is number of parameters in model, etc. ) but rather by w_ii*h_ii*r_i^2/(1-hii)^2 divided by k*s^2, (2) i.e. has the weight in there. Apart from the division this is sum of weighted squares of differences yhat_j - yhat_j[i]. (That is, it is the weighted sum of squares of fits minus fits with ith point deleted.) However, a littl...