**Syntax**

` >>>> CORRELATION: (-) rcorr`

**Parent Command**

` >>> SELECT
`

**Subcommand**

` -
`

**Description**

This command defines one of the criteria used for automatic parameter selection. It examines the ratio between the apparent conditional standard deviation sigma* and the joint standard deviation sigma as a measure of overall parameter correlation (since the calculation is performed far from the minimum, the standard deviations cannot be interpreted as actual estimation uncertainties):

X = sigma*/sigma (O < X < 1)Those parameters with a ratio larger than |*rcorr*|, i.e., the most independent parameters, are selected. Strongly correlated parameters are (temporarily) excluded from the optimization process. If a negative value is given for *rcorr*, the selection criterion is relaxed with each iteration k, and reaches zero for the last iteration *max_iter*, i.e., all parameters are selected for the final step.

*rcorr*_{k} = |*rcorr*|*(1-k/*max_iter*)The choice for *rcorr* depends on the number of parameters n specified in block `> PARAMETER`. As more parameters are estimated simultaneously, the higher parameter interdependencies become. This fact should be acknowledged by specifying a smaller value for |*rcorr*| if n increases.

**Example**

` > COMPUTATION
>> OPTION
>>> SELECT parameter automatically every
>>>> : 3 ITERATIONS
>>>> based on the CORRELATION criterion with `

*rcorr*: -0.10 <<<< <<< <<

**See Also**

` >>>> ITERATION (s) | >>>> SENSITIVITY
`