Calculation of backfit values from a fitted dose-response model

By inverse regression backfitted dose values are calculated for the mean response per dose.

Usage

backfit(drcObject)

Arguments

drcObject

an object of class 'drc'.

Value

Two columns with the original dose values and the corresponding backfitted values using the fitted dose-response model. For extreme dose values (e.g., high dose) the backfitted values may not be well-defined.

See also

A related function is ED.drc.

Author

Christian Ritz after a suggestion from Keld Sorensen.

Examples

ryegrass.LL.4 <- drm(rootl~conc, data=ryegrass, fct=LL.4())

backfit(ryegrass.LL.4)
#> Warning: NaNs produced
#>       dose   Estimate
#> [1,]  0.00  0.5500692
#> [2,]  0.94  0.7743783
#> [3,]  1.88  1.8744292
#> [4,]  3.75  3.7830500
#> [5,]  7.50  7.0811832
#> [6,] 15.00 10.1667582
#> [7,] 30.00        NaN