## Fitting a four-parameter log-logistic model
ryegrass.m1 <- drm(rootl ~conc, data = ryegrass, fct = LL.4())
## Displaying the residual plot (raw residuals)
plot(fitted(ryegrass.m1), residuals(ryegrass.m1))
## Using the standardised residuals
plot(fitted(ryegrass.m1), residuals(ryegrass.m1, type = "standard"))
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