rocplot {Zelig} | R Documentation

## Receiver Operator Characteristic Plots

### Description

The `rocplot` command generates a receiver operator characteristic plot to compare the in-sample (default) or out-of-sample fit for two logit or probit regressions.

### Usage

    rocplot(y1, y2, fitted1, fitted2, cutoff = seq(from=0, to=1, length=100),
            lty1 = "solid", lty2 = "dashed", lwd1 = par("lwd"), lwd2 = par("lwd"),
            col1 = par("col"), col2 = par("col"), main, xlab, ylab,
            plot = TRUE, ...)

### Arguments

`y1` | Response variable for the first model.
`y2` | Response variable for the second model.
`fitted1` | Fitted values for the first model. These values may represent either the in-sample or out-of-sample fitted values.
`fitted2` | Fitted values for the second model.
`cutoff` | A vector of cut-off values between 0 and 1, at which to evaluate the proportion of 0s and 1s correctly predicted by the first and second model. By default, this is 100 increments between 0 and 1, inclusive.
`lty1, lty2` | The line type for the first model (`lty1`) and the second model (`lty2`), defaulting to solid and dashed, respectively.
`lwd1, lwd2` | The width of the line for the first model (`lwd1`) and the second model (`lwd2`), defaulting to 1 for both.
`col1, col2` | The colors of the line for the first model (`col1`) and the second model (`col2`), defaulting to black for both.
`main` | a title for the plot. Defaults to `ROC Curve`.
`xlab` | a label for the x-axis. Defaults to `Proportion of 1's Correctly Predicted`.
`ylab` | a label for the y-axis. Defaults to `Proportion of 0's Correctly Predicted`.
`plot` | defaults to `TRUE`, which generates a plot to the selected device. If `FALSE`, returns a list of items (see below).
`...` | Additional parameters passed to plot, including `xlab`, `ylab`, and `main`.

### Value

If `plot = TRUE`, `rocplot` generates an ROC plot for two logit or probit models. If `plot = FALSE`, `rocplot` returns a list with the following elements:

`roc1` | a matrix containing a vector of x-coordinates and y-coordinates corresponding to the number of ones and zeros correctly predicted for the first model.
`roc2` | a matrix containing a vector of x-coordinates and y-coordinates corresponding to the number of ones and zeros correctly predicted for the second model.
`area1` | the area under the first ROC curve, calculated using Reimann sums.
`area2` | the area under the second ROC curve, calculated using Reimann sums.

### Author(s)

Kosuke Imai <kimai@princeton.edu>; Gary King <king@harvard.edu>; Olivia Lau <olau@fas.harvard.edu>

### See Also

The full Zelig manual (available at http://gking.harvard.edu/zelig), `plot`, `lines`.

### Examples

    data(turnout)
    z.out1 <- zelig(vote ~ race + educate + age, model = "logit",
      data = turnout)
    z.out2 <- zelig(vote ~ race + educate, model = "logit",
      data = turnout)
    rocplot(z.out1$y, z.out2$y, fitted(z.out1), fitted(z.out2))

[Package Zelig version 3.4-3 Index]