Hello,

I am trying to fit my Elisa results (absorbance readings)  to a standard
curve. To create the standard curve model, I performed a 4-parameter
logistic fit using the 'drc' package (ExpectedConc~Absorbance). This gave me
the following:
> FourP

A 'drc' model.

Call:
drm(formula = Response ~ Expected, data = SC, fct = LL.4())

Coefficients:
b:(Intercept)  c:(Intercept)  d:(Intercept)  e:(Intercept)
        1.336          6.236         85.521         59.598

> summary(FourP)

Model fitted: Log-logistic (ED50 as parameter) (4 parms)

Parameter estimates:

              Estimate Std. Error  t-value p-value
b:(Intercept)  1.33596    0.15861  8.42309  0.0011
c:(Intercept)  6.23557    3.18629  1.95700  0.1220
d:(Intercept) 85.52140    2.15565 39.67313  0.0000
e:(Intercept) 59.59835    5.18781 11.48815  0.0003

Residual standard error:

 1.866876 (4 degrees of freedom)

Now that I have the 4 parameters, how do I fit the absorbance readings for
the analytical unknowns to the standard curve model (as to estimate the
concentrations of my unknown analytical samples)?
I can use the argument 'predict', but this predicts absorbance given
concentrations (y given x), I need to predict concentrations give absorbance
(x given y).

Thanks!
Chris

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