Generating a diagnostic plot of a fitted model

Diagnostics are methods to evaluate assumptions of the regression, which can be used to determine whether a fitted model adequately represents the data. In the following recipe, we introduce how to diagnose a regression model through the use of a diagnostic plot.

Getting ready

You need to have completed the previous recipe by computing a linear model of the x and y1 variables from the quartet, and have the model assigned to the lmfit variable.

How to do it...

Perform the following step to generate a diagnostic plot of the fitted model:

  1. Plot the diagnostic plot of the regression model:
    > par(mfrow=c(2,2))
    > plot(lmfit)
    

    Diagnostic plots of the regression model

How it works...

The plot function generates four ...

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