Calculation of backfit values from a fitted dose-response model

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

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 the example below).

References

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See also

A related function is ED.drc.

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