Thank you Jason and Paige for your input it has been VERY helpful. I am also confused about another topic and I was hoping one of you might hold the answer. I am trying to examine influential observation in some logistic regression models. I am aware that the INFLUENTIAL option and the OUTPUT OUT= options can be used to generate certain statistics such as DFBetas, Leverage(hat) values and Pearson and Deviance residuals. I am using ceratin cut-off values which I have read from a few books to subset the influential observations based on the DFBetas and Leverage(hat)values from the output from INFLUENTIAL. However, I am not sure what cut off values I can use to identify inlfuential observations for the Deviance and Pearson residuals? Are these values standardised in the outputs from INFLUENTIAL and OUTPUT OUT= ? If so can I just use the absolute value of 2 or 3 as in standardised residuals in linear regression. I am aware that you can generate plots of the residuals aswel but I was hoping there might be a cut off value that I could use aswel. I am also unfamiliar with the notation that comes along side them in the INFLUENTIAL output, i.e. there is a 1 unit= some value beside each statistic in the output. Are these values used to detect the influential observations and how are they used? I apologise for the long message, but any help would be much appreciated! thanks, Frewen
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