value {verification} | R Documentation

## Forecast Value Function

### Description

Calculates the economic value of a forecast based on a cost/loss ratio.

### Usage

    value(obs, pred= NULL, baseline = NULL, cl = seq(0.05, 0.95, 0.05), plot = TRUE, all = FALSE, thresholds = seq(0.05, 0.95, 0.05), ylim = c(-0.05, 1), xlim = c(0,1), ...)

### Arguments

`obs` | A vector of binary observations or a contingency table summary of values in the form c(n11, n01, n10, n00) where in nab a = obs, b = forecast.
`pred` | A vector of probabilistic predictions.
`baseline` | Baseline or naive forecast. Typically climatology.
`cl` | Cost loss ratio. The relative value of being unprepared and taking a loss to that of un-necessarily preparing. For example, cl = 0.1 indicates it would cost $ 1 to prevent a $10 loss. This defaults to the sequence 0.05 to 0.95 by 0.05.
`plot` | Should a plot be created? Default is TRUE
`all` | In the case of probabilistic forecasts, should value curves for each thresholds be displayed.
`thresholds` | Thresholds considered for a probabilistic forecast.
`ylim, xlim` | Plotting options.
`...` | Options to be passed into the plotting function.

### Value

If assigned to an object, the following values are reported.

`vmax` | Maximum value
`V` | Vector of values for each cl value
`F` | Conditional false alarm rate.
`H` | Conditional hit rate
`cl` | Vector of cost lost ratios.
`s` | Base rate

### Author(s)

Matt Pocernich <pocernic@rap.ucar.edu>

### References

Jolliffe, Ian and David B. Stephensen (2003) Forecast Verification: A Practioner's Guide in Atmospheric Science, Chapter 8. Wiley

### Examples

    ## value as a contingency table
    ## Finley tornado data
    obs<- c(28, 72, 23, 2680)
    value(obs)
    aa <- value(obs)
    aa$Vmax # max value

    ## probabilistic forecast example
     obs  <- round(runif(100) )
     pred <-  runif(100)

    value(obs, pred, main = "Sample Plot",
                 thresholds = seq(0.02, 0.98, 0.02) )
    ##########
    data(pop)
    pop.convert()

    value(obs = d$obs_rain, pred = d$p24_rain, all = TRUE)

[Package verification version 1.20 Index]