weighted normal errors regression weighted normal errors regression weighted normal error regression weighted error definition weighted normal errors regression with censoring weighted normal error regression weighted normal error regression can weighted normal errors be corrected with tobit censoring regression model weighted normal error regression censored error weighted model weighted normal error regression with censoring weighted average errors regression what is weighted normal error with censoring weighted normal errors regression with censoring weighted normal errors regression with weighted variance weighted normal error regression weighted normal error regression weighted normal errors regression weighted normal error regression model