Poisson Regression - Optionsmain topic see also
Poisson Regression - OptionsStat > Regression > Poisson Regression > Fit Poisson Model > Options
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Link Functions Minitab provides three link functions, allowing you to fit a broad class of Poisson response models. You want to choose a link function that results in a good fit to your data. Goodness-of-fit statistics can be used to compare the fits using different link functions. Certain link functions may be used for historical reasons or because they have a special meaning in a discipline.
Log: Choose to use the log link function. The log link function is the canonical link function for Poisson regression.
Square root: Choose to use the square root link function.
Identity: Choose to use the identity link function.
Weights: Enter a numeric column of weights to perform weighted regression. Weights must be greater than or equal to zero. The length of the weights column must match the length of the response column.
Confidence level for all intervals: Enter the confidence level. The default is 95.
Type of confidence interval: Choose the type of confidence interval: two-sided (default), lower bound, or upper bound.
Residuals for diagnostics: Choose between Pearson's and Deviance residuals. Both types of residuals help to find patterns in the residual plots and outliers. When the model uses the log link function, the distribution of the deviance residuals is more similar to the distribution of the residuals from least squares models.
Deviances for Tests: Choose a deviance for calculating chi-square values and p-values. Typically, use the adjusted deviance. Use sequential deviance to determine the significance of terms by the order that they enter the model.
Adjusted deviances: Measures the reduction in the deviance for each term relative to a model that contains all of the remaining terms.
Sequential deviances: Measures the reduction in the deviance when a term is added to a model that contains only the terms before it.