invest: Estimate the concentration given a response value

In drLumi: Multiplex Immunoassays Data Analysis

Description

Estimates the inverse of the funtion. Given a response value, estimates the corresponding concentration value and the standard error.

Usage

invest(x, analyte=NULL, yvalue, ci.method = c("delta", "bootstrap"),
        level = 0.95, seed.boot = 123, nboot = 100)

Arguments

x	a scluminex object.
analyte	the specific analyte to estimate the invert values. Default NULL (all analytes).
yvalue	value of the response model to estimate the inverse in log10 scale.
ci.method	character defining the method to be applied for estimating standard error ('delta' or 'bootstrap'). Default 'delta'.
level	confidence level. Default 0.95.
seed.boot	numeric for the seed of the bootstrap method. Only applies for bootstrap method. Default 123.
nboot	number of bootstrap replicates. Only applies for bootstrap method. Default 100.

Details

Delta method function used is deltamethod from the msm package. Bootstrap method generates nboot response vectors (assuming normality) and fit the same model with original concentration data. The confidence interval is calculated by the percentile method specified in the level argument (1-level/2, 1-(1-level)/2).

Value

A data.frame with the following components:

• MFI variable, the yvalue response vector

• Fit of the concentration, concentration estimation of the yvalue vector

• Fit of the concentration.lci, lower confidence bounds for the concentration estimation

• Fit of the concentration.uci, upper confidence bounds for the concentration estimation

• Fit of the concentration.se, estimation of the Standard Error of the concentration. If ci.method 'bootstrap' is NA

Examples

# Load data
data(ecdata)
data(mfidata)

dat <- mfidata[mfidata$plate=="plate_1" & mfidata$analyte=="FGF",]

# Estimate models
sdf <- data_selection(dat, ecdata)[[1]]
igmodels <- scluminex("plate_1",sdf$standard, sdf$background,
lfct="SSl4", bkg="ignore", fmfi="mfi", verbose=FALSE)

# Delta
invest(igmodels, "FGF", c(2, 2.5, 3),  "delta")

# Bootstrap
invest(igmodels, "FGF" ,c(2, 2.5, 3), "bootstrap", nboot=10)

drLumi documentation built on May 2, 2019, 2:45 p.m.