Here is my problem which hours on the Internet has yet to resolve. I have a log-log linear regression with just an X and Y, Even with Log-log, the normal prob plot is turned down or up at each end, nice and straight in-between. HOWEVER, the residual plot has a distinctive negative slope where, as X grows, the residual goes from almost total > 0 until it finally goes negative for the larger Xs; the variance seems more or less constant. What is that residual pattern telling me? Does anyone have an idea?
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