hillConcCorrect: Hill-Based Concentration Correction

Description Usage Arguments Details Value Author(s) See Also Examples

Description

Estimates actual underlying concentrations leading to a given set of response measurements based on the assumption that actual concentrations are log-normally distributed around target concentrations, response errors are normally distributed, and the actual underlying relationship between concentration and response is represented by the given Hill dose-response model.

Usage

1
hillConcCorrect(conc, act, parv, sigr = 1)

Arguments

conc

a vector of expected or target concentrations, around which actual concentrations are assumed to be log-normally distributed

act

a vector of response values

parv

a four-parameter vector specifying a Hill model as described in evalHillEqn which is assumed to be the actual relationship between concentration and response

sigr

the estimated ratio of the noises in response- and log (base10) concentration-space

Details

Suppose that c' is a given target concentration, and c is the actual concentration in given well, plate, or condition. Suppose also that y is the actual response that would result from the concentration in the given Hill dose-response model, and y' is the measured response value. This function assumes that

y' ~ N(y,sigma)

log10(c) ~ N(log10(c'),sigma/r)

for some sigma, where N is a normal distribution, and r is the ratio specified by the parameter sigr. Based on these assumptions, the function uses Bayes' rule to calculate the maximum likelihood estimate of c for every given value of c' and y'.

Value

A vector of concentrations representing the maximum likelihood estimates of the actual concentrations which produced the given responses.

Author(s)

Nathaniel R. Twarog

See Also

evalHillEqn, runBRAIDanalysis

Examples

1
2
3
4
5
6
data(es8olatmz)
drv <- es8olatmz$compound2=="DMSO"
hfit <- findBestHill(act~conc1,es8olatmz[drv,],defaults=c(0,-2.7))
drvpos <- drv & es8olatmz$conc1>0
cconc <- hillConcCorrect(es8olatmz$conc1[drvpos],es8olatmz$act[drvpos],
			coef(hfit$allfits[[hfit$bestModIdx]]),sigr=1)

braidrm documentation built on May 1, 2019, 10:24 p.m.