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help for rvfplot2
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Plot residuals versus fitted values after model fit

rvfplot2 [, residualtype qualifier rscale(exp) fscale(exp)
lowess[(lowess_options)] scatter_options plot(plot) ]

Description

rvfplot2 graphs a residual-versus-fitted plot, a graph of the residuals
versus the fitted values. The residuals are, by default, those calculated
by predict, residuals or (if the previous estimation command was glm) by
predict, response. The fitted values are those produced by predict by
default after each estimation command.

rvfplot2 is for use after regress and similar commands; see help on the
command of interest. It is a generalisation of rvfplot in official Stata.

Options

residualtype specifies a type of residual other than the default.  The
following types are currently supported: anscombe, deviance,
likelihood, pearson, residuals, response, rstandard, rstudent, score,
working.

qualifier specifies one of standardized, studentized, modified, adjusted.

rscale(exp) specifies a transformed scale on which to show the residuals
using Stata syntax and X as a placeholder for the residual variable
name. Thus rscale(X^2) specifies squaring, to show relative
contribution to residual variance; rscale(abs(X)) specifies absolute
value, to set aside sign; rscale(sqrt(abs(X))) specifies root of
absolute value, a useful scale on which to check for
heteroscedasticity.

fscale(exp) specifies a transformed scale on which to show the fitted
values using Stata syntax and X as a placeholder for the fitted
variable name. Thus for example fscale(2 * ln(X)) specifies twice the
natural logarithm, which is the constant information scale for a
generalised linear model with gamma error. Similarly, arguments of 2
* sqrt(X), 2 * asin(sqrt(X)), and -2 / sqrt(X) specify the constant
information scale for Poisson, binomial and inverse Gaussian errors
respectively. See McCullagh and Nelder (1989, p.398) for background.

lowess[(lowess_options)] specifies that the residuals will be smoothed as
a function of the fitted using twoway lowess (options may be
specified).

scatter_options are options of twoway scatter.

plot(plot) provides a way to add other plots to the generated graph; see
plot_option.

Examples

. gen forxmpg = foreign * mpg
. regress price weight mpg forxmpg foreign
. rvfplot2

. anova price rep foreign rep*foreign weight, cont(weight)
. rvfplot2, rscale(sqrt(abs(X)))

. glm price weight, link(log)
. rvfplot2, anscombe yli(0)

. glm price weight, link(log)
. rvfplot2, anscombe yli(0) lowess
. rvfplot2, anscombe yli(0) lowess(bw(0.9))

Author

Nicholas J. Cox, University of Durham, U.K.
n.j.cox@durham.ac.uk

Acknowledgements

Phil Ender provided very helpful comments on a previous version.

References

McCullagh, P. and Nelder, J.A. 1989. Generalized linear models.  London:
Chapman and Hall.

Also see

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