leps: Linear Error in Probability Space (LEPS)

In verification: Weather Forecast Verification Utilities

Description

Calculates the linear error in probability spaces. This is the mean absolute difference between the forecast cumulative distribution value (cdf) and the observation. This function creates the empirical cdf function for the observations using the sample population. Linear interpretation is used to estimate the cdf values between observation values. Therefore; this may produce awkward results with small datasets.

Usage

 leps(x, pred, plot = TRUE, ... )
                         

Arguments

x	A vector of observations or a verification object with “cont.cont” properties.
pred	A vector of predictions.
plot	Logical to generate a plot or not.
...	Additional plotting options.

Value

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

leps.0	Negatively oriented score on the [0,1] scale, where 0 is a perfect score.
leps.1	Positively oriented score proposed by Potts.

Author(s)

Matt Pocernich

References

DeQue, Michel. (2003) “Continuous Variables” Chapter 5, Forecast Verification: A Practitioner's Guide in Atmospheric Science.

Potts, J. M., Folland, C.K., Jolliffe, I.T. and Secton, D. (1996) “Revised ‘LEPS’ scores fore assessing climate model simulations and long-range forecasts.” J. Climate, 9, pp. 34-54.

Examples

 obs <- rnorm(100, mean = 1, sd = sqrt(50))
 pred<-  rnorm(100, mean = 10, sd = sqrt(500))

 leps(obs, pred, main = "Sample Plot") 
## values approximated

OBS <- c(2.7, 2.9, 3.2, 3.3, 3.4, 3.4, 3.5, 3.8, 4, 4.2, 4.4, 4.4, 4.6,
5.8, 6.4)
PRED <- c(2.05, 3.6, 3.05, 4.5, 3.5, 3.0, 3.9, 3.2, 2.4, 5.3, 2.5, 2.8,
3.2, 2.8, 7.5)

a <- leps(OBS, PRED)
a

Example output

Loading required package: fields
Loading required package: spam
Loading required package: dotCall64
Loading required package: grid
Spam version 2.1-1 (2017-07-02) is loaded.
Type 'help( Spam)' or 'demo( spam)' for a short introduction 
and overview of this package.
Help for individual functions is also obtained by adding the
suffix '.spam' to the function name, e.g. 'help( chol.spam)'.

Attaching package: 'spam'

The following objects are masked from 'package:base':

    backsolve, forwardsolve

Loading required package: maps
Loading required package: boot
Loading required package: CircStats
Loading required package: MASS
Loading required package: dtw
Loading required package: proxy

Attaching package: 'proxy'

The following object is masked from 'package:spam':

    as.matrix

The following objects are masked from 'package:stats':

    as.dist, dist

The following object is masked from 'package:base':

    as.matrix

Loaded dtw v1.18-1. See ?dtw for help, citation("dtw") for use in publication.

$leps.0
[1] 0.3733333

$leps.1
[1] 0.04622222

verification documentation built on May 2, 2019, 1:24 a.m.