LCxt {morseTKTD} | 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., |
t |
A number giving the time at which |
... |
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\ ofLC_{X}
at timetime_LCx
forX
\df_doseA
data.frame
with four columns:concentration
, and medianq50
and 95\ (qinf95
andqsup95
) of the survival probability at timetime_LCx
.