Add degrees of freedom by OMEGA/SIGMA block

Calculate and add degrees of freedom to be used for simulation using the inverse Wishart distribution.

Usage

NWPRI_df(pars)

Arguments

pars: Parameters in long format, as returned by `NMreadExt()`.

Value

A data.table with DF2 added. See details.

Details

The degrees of freedom are calculated as DF = 2*((est**2)/(se**2)) + 1 -blocksize-1 DF2 is then adjusted to not be greater than the blocksize, and the minumum degrees of freedom observed in the block is applied to the full block. For fixed parameters, DF2 equals the blocksize.

References

inverse-Wishart degrees of freedom calculation for OMEGA and SIGMA: NONMEM tutorial part II, supplement 1, part C.