LCxt: Predict Lethal Concentration at any specified time point.
In morseTKTD: Bayesian Inference of TKTD Models

LCxt	R Documentation

Predict Lethal Concentration at any specified time point.

Description

Predict the Lethal Concentration at any specified time point for a SurvFit object.

The function LCx, x\ the dose required to kill x\ after a specified test duration (time_LCx) (default is the maximum time point of the experiment).

Mathematical definition of x\ denoted LC(x,t), is:

S(LC(x,t), t) = S(0, t)*(1- x/100),

where S(LC(x,t), t) is the survival probability at concentration LC(x,t) at time t, and S(0,t) is the survival probability at no concentration (i.e. concentration is 0) at time t which reflect the background mortality h_b:

S(0, t) = exp(-hb* t).

In the function LCx, we use the median of S(0,t) to rescale the x\

Usage

lcxt(fit, x, t, ...)

## S3 method for class 'SurvFit'
lcxt(
  fit,
  x = 0.5,
  t = NULL,
  exposure_range = NULL,
  interpolate_length = 50,
  ...
)

Arguments

`fit`	An object used to select a method
`x`	rate of individuals dying (e.g., `0.5` for `LC_{50}`, `0.1` for `LC_{10}`, ...).
`t`	A number giving the time at which `LC_{x}` has to be estimated. If NULL, the latest time point of the experiment is used.
`...`	Further arguments to be passed to generic methods
`exposure_range`	A vector of length 2 with minimal and maximal value of the range of concentration. If NULL, the range is define between 0 and the highest tested concentration of the experiment.
`interpolate_length`	of time point in the range of concentration between 0 and the maximal concentration. 100 by default. description.

Value

The function returns an object of class LCx, which is a list with the following information:

X_propSurvival probability of individuals surviving considering the median of the background mortality (i.e. S(0, t)*(1- x/100)).
X_prop_providedSurvival probability of individuals surviving as provided in arguments (i.e. (100-X)/100).
time_LCxA number giving the time at which LC_{x} has to be estimated as provided in arguments or if NULL, the latest time point of the experiment is used.
df_LCxA data.frame with quantiles (median, 2.5\ of LC_{X} at time time_LCx for X\
df_doseA data.frame with four columns: concentration, and median q50 and 95\ (qinf95 and qsup95) of the survival probability at time time_LCx.