fitgnls {tcplfit2}

Gain-Loss Model Fit

Description

Function that fits to f(x) = \frac{tp}{[(1 + (ga/x)^p )(1 + (x/la)^q )]} and returns generic model outputs.

Usage

fitgnls(
  conc,
  resp,
  bidirectional = TRUE,
  verbose = FALSE,
  nofit = FALSE,
  minwidth = 1.5
)

Arguments

conc

Vector of concentration values NOT in log units.

resp

Vector of corresponding responses.

bidirectional

If TRUE, model can be positive or negative; if FALSE, it will be positive only.

verbose

If TRUE, gives optimization and hessian inversion details.

nofit

If nofit = TRUE, returns formatted output filled with missing values.

minwidth

Minimum allowed distance between gain ac50 and loss ac50 (in log10 units).

Details

Concentrations are converted internally to log10 units and optimized with f(x) = \frac{tp}{[(1 + 10^{(p*(ga-x))} )(1 + 10^{(q*(x-la))} )]}, then ga, la, ga_sd, and la_sd are converted back to regular units before returning. Zero background and increasing initial absolute response are assumed. Parameters are "tp" (top), "ga" (gain AC50), "p" (gain power), "la" (loss AC50),"q" (loss power) and error term "er". success = 1 for a successful fit, 0 if optimization failed, and NA if nofit = TRUE. cov = 1 for a successful hessian inversion, 0 if it fails, and NA if nofit = TRUE. aic, rme, modl, parameters, and parameter sds are set to NA in case of nofit or failure.

Value

Named list containing: success, aic (Akaike Information Criteria), cov (success of covariance calculation), rme (root mean square error), modl (vector of model values at given concentrations), parameters values, parameter sd (standard deviation) estimates, pars (vector of parameter names), sds (vector of parameter sd names).

Examples

fitgnls(c(.03,.1,.3,1,3,10,30,100), c(0,.3,1, 2, 2.1, 1.5, .8, .2))