reliability.plot: Reliability Plot
In verification: Weather Forecast Verification Utilities

Description Usage Arguments Details Note Author(s) References Examples

A reliability plot is a simple form of an attribute diagram that depicts the performance of a probabilistic forecast for a binary event. In this diagram, the forecast probability is plotted against the observed relative frequency. Ideally, this value should be near to each other and so points falling on the 1:1 line are desirable. For added information, if one or two forecasts are being verified, sharpness diagrams are presented in the corners of the plot. Ideally, these histograms should be relatively flat, indicating that each bin of probabilities is use an appropriate amount of times.

   ## Default S3 method:
reliability.plot(x, obar.i, prob.y, titl = NULL, legend.names = NULL, ... )
## S3 method for class 'verify'
reliability.plot(x, ...)

`x`	Forecast probabilities.(y_i) or a “prob.bin” class object from `verify`.
`obar.i`	Observed relative frequency \bar{o}_i.
`prob.y`	Relative frequency of forecasts
`titl`	Title
`legend.names`	Names of each model that will appear in the legend.
`...`	Graphical parameters.

This function works either by entering vectors or on a verify class object.

If a single prob.bin class object is used, a reliability plot along with a sharpness diagram is displayed. If two forecasts are provided in the form of a matrix of predictions, two sharpness diagrams are provided. If more forecasts are provided, the sharpness diagrams are not displayed.

Matt Pocernich

Wilks, D. S. (1995) Statistical Methods in the Atmospheric Sciences Chapter 7, San Diego: Academic Press.

## Data from Wilks, table 7.3 page 246.
 y.i   <- c(0,0.05, seq(0.1, 1, 0.1))
 obar.i <- c(0.006, 0.019, 0.059, 0.15, 0.277, 0.377, 0.511,
    0.587, 0.723, 0.779, 0.934, 0.933)

 prob.y <- c(0.4112, 0.0671, 0.1833, 0.0986, 0.0616, 0.0366,
    0.0303,  0.0275, 0.245, 0.022, 0.017, 0.203) 

 obar <- 0.162

reliability.plot(y.i, obar.i, prob.y, titl = "Test 1", legend.names =
c("Model A") )


## Function will work with a ``prob.bin'' class object as well.
## Note this is a very bad forecast.
obs<- round(runif(100))
pred<- runif(100)

A<- verify(obs, pred, frcst.type = "prob", obs.type = "binary")

reliability.plot(A, titl = "Alternative plot")