drLumi (version 0.1.2)

SSl4: Self-Starting Nls 4 parameters logistic regression model

Description

This selfStart model evaluates the 4 parameters logistic regression model and its gradient. It has an initial attribute that will evaluate initial estimates of the parameters hAsym, lAsym, Slope and xMid for a given set of data Instead of the standard exp function this implementation use the 10^ function. $$f(x)=lAsym +\frac{hAsym-lAsym}{1+10^{Slope(x-xMid)}}$$

Usage

SSl4(x, Slope, lAsym, hAsym, xMid)

Arguments

x

a numeric vector of values at which to evaluate the model

Slope

a numeric parameter representing the -slope of the function at the inflection point

lAsym

a numeric parameter representing the lower asymptote when x trend to -Inf

hAsym

a numeric parameter representing the higher asymptote when x trend to Inf

xMid

is the x value corresponding to the inflection point

Value

• The value returned is a list containing the nonlinear function, the self starter function and the parameter names.

format

A selfStart model

Examples

# Load data
data(ecdata)
data(mfidata)

# Select analyte FGF for plate 1
dat <- mfidata[mfidata$plate=="plate_1" & mfidata$analyte=="FGF",]

sdf <- data_selection(dat, ecdata)[[1]]

ig <- scluminex("plate_1",sdf$standard, sdf$background,
           lfct="SSl4",
           bkg="ignore",
           fmfi="mfi",
           verbose=FALSE)

summary(ig)