DualEndpointBeta-class | R Documentation |
DualEndpointBeta
DualEndpointBeta
is the class for the dual endpoint model with beta
function for dose-biomarker relationship.
DualEndpointBeta(E0, Emax, delta1, mode, ref_dose_beta = 1, ...)
.DefaultDualEndpointBeta()
E0 |
( |
Emax |
( |
delta1 |
( |
mode |
( |
ref_dose_beta |
( |
... |
parameters passed to |
This class extends the DualEndpoint
class so that the dose-biomarker
relationship f(x)
is modelled by a parametric, rescaled beta density
function:
f(x) = E0 + (Emax - E0) * Beta(delta1, delta2) * (x/x*)^{delta1} * (1 - x/x*)^{delta2},
where x*
is the maximum dose (end of the dose range to be considered),
delta1
and delta2
are the two beta function parameters, and
E0
, Emax
are the minimum and maximum levels, respectively.
For ease of interpretation, we use the parametrization based on delta1
and the mode, where
mode = delta1 / (delta1 + delta2),
so that multiplying this by x*
gives the mode on the dose grid.
All parameters can currently be assigned uniform distributions or be fixed
in advance. Note that E0
and Emax
can have negative values or
uniform distributions reaching into negative range, while delta1
and
mode
must be positive or have uniform distributions in the positive
range.
E0
(numeric
)
either a fixed number or the two uniform distribution
parameters.
Emax
(numeric
)
either a fixed number or the two uniform
distribution parameters.
delta1
(numeric
)
either a fixed positive number or the two
parameters of the uniform distribution, that can take only positive values.
mode
(numeric
)
either a fixed positive number or the two
parameters of the uniform distribution, that can take only positive values.
ref_dose_beta
(positive_number
)
the reference dose x*
(note
that this is different from the ref_dose
in the inherited DualEndpoint
model).
Typically, end users will not use the .DefaultDualEndpointBeta()
function.
DualEndpoint
, DualEndpointRW
, DualEndpointEmax
.
my_model <- DualEndpointBeta(
mean = c(0, 1),
cov = matrix(c(1, 0, 0, 1), nrow = 2),
ref_dose = 10,
use_log_dose = TRUE,
sigma2W = c(a = 0.1, b = 0.1),
rho = c(a = 1, b = 1),
E0 = c(0, 100),
Emax = c(0, 500),
delta1 = c(0, 5),
mode = c(1, 15),
ref_dose_beta = 1000
)
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