# plot.betareg: Diagnostic Plots for betareg Objects In betareg: Beta Regression

## Description

Various types of standard diagnostic plots can be produced, involving various types of residuals, influence measures etc.

## Usage

 ```1 2 3 4 5 6 7 8``` ```## S3 method for class 'betareg' plot(x, which = 1:4, caption = c("Residuals vs indices of obs.", "Cook's distance plot", "Generalized leverage vs predicted values", "Residuals vs linear predictor", "Half-normal plot of residuals", "Predicted vs observed values"), sub.caption = paste(deparse(x\$call), collapse = "\n"), main = "", ask = prod(par("mfcol")) < length(which) && dev.interactive(), ..., type = "sweighted2", nsim = 100, level = 0.9) ```

## Arguments

 `x` fitted model object of class `"betareg"`. `which` numeric. If a subset of the plots is required, specify a subset of the numbers `1:6`. `caption` character. Captions to appear above the plots. `sub.caption` character. Common title-above figures if there are multiple. `main` character. Title to each plot in addition to the above `caption`. `ask` logical. If `TRUE`, the user is asked before each plot. `...` other parameters to be passed through to plotting functions. `type` character indicating type of residual to be used, see `residuals.betareg`. `nsim` numeric. Number of simulations in half-normal plots. `level` numeric. Confidence level in half-normal plots.

## Details

The `plot` method for `betareg` objects produces various types of diagnostic plots. Most of these are standard for regression models and involve various types of residuals, influence measures etc. See Ferrari and Cribari-Neto (2004) for a discussion of some of these displays.

The `which` argument can be used to select a subset of currently six supported types of displays. The corresponding element of `caption` contains a brief description. In some more detail, the displays are: Residuals (as selected by `type`) vs indices of observations (`which = 1`). Cook's distances vs indices of observations (`which = 2`). Generalized leverage vs predicted values (`which = 3`). Residuals vs linear predictor (`which = 4`). Half-normal plot of residuals (`which = 5`), which is obtained using a simulation approach. Predicted vs observed values (`which = 6`).

## References

Cribari-Neto, F., and Zeileis, A. (2010). Beta Regression in R. Journal of Statistical Software, 34(2), 1–24. http://www.jstatsoft.org/v34/i02/.

Ferrari, S.L.P., and Cribari-Neto, F. (2004). Beta Regression for Modeling Rates and Proportions. Journal of Applied Statistics, 31(7), 799–815.

`betareg`
 ```1 2 3 4 5 6 7``` ```data("GasolineYield", package = "betareg") gy <- betareg(yield ~ gravity + pressure + temp10 + temp, data = GasolineYield) par(mfrow = c(3, 2)) plot(gy, which = 1:6) par(mfrow = c(1, 1)) ```