Find.Optim.Stat {biomod2} R Documentation

## Calculate the best score according to a given evaluation method

### Description

`Find.Optim.Stat` is an internal biomod2 function to find the threshold to convert continuous values into binary ones leading to the best score for a given evaluation metric.

### Usage

```Find.Optim.Stat(Stat='TSS',
Fit,
Obs,
Nb.thresh.test = 100,
Fixed.thresh = NULL)
```

### Arguments

 `Stat` either 'ROC', TSS', 'KAPPA', 'ACCURACY', 'BIAS', 'POD', 'FAR', 'POFD', 'SR', 'CSI', 'ETS', 'HK', 'HSS', 'OR' or 'ORSS' `Fit` vector of fitted values (continuous) `Obs` vector of observed values (binary) `Nb.thresh.test` integer, the numer of thresholds tested over the range of fitted value `Fixed.thresh` integer, if not `NULL`, the only threshold value tested

### Details

Please refer to `BIOMOD_Modeling` to get more information about this metrics. If you give a `Fixed.thresh`, no optimisation will be done. Only the score for this threshold will be returned.

### Value

A 1 row x 4 column `matrix` :

• `best.iter`: the best score obtained for chosen statistic

• `cutoff`: the associated cut-off used for transform fitted vector into binary

• `sensibility`: the sensibility with this threshold

• `specificity`: the specificity with this threshold

### Author(s)

Damien Georges

`BIOMOD_Modeling`, `getStatOptimValue`, `calculate.stat`

### Examples

```  a <- sample(c(0,1),100, replace=TRUE)

##' random drawing
b <- runif(100,min=0,max=1000)
Find.Optim.Stat(Stat='TSS',
Fit=b,
Obs=a)

##' biased drawing
BiasedDrawing <- function(x, m1=300, sd1=200, m2=700, sd2=200){
return(ifelse(x<0.5, rnorm(1,m1,sd1), rnorm(1,m2,sd2)))
}

c <- sapply(a,BiasedDrawing)

Find.Optim.Stat(Stat='TSS',
Fit=c,
Obs=a,
Nb.thresh.test = 100)

```

[Package biomod2 version 3.5.1 Index]