
Dose–exposure and exposure–response models for longitudinal data 45
vary between subjects. For example, the model (2.5) w ith random variations
in the parameters can be written as
c
i
(t) =
DK
ai
F
V
i
(K
ai
− Cl
i
/V
i
)
(exp(−Cl
i
/V
i
t) − exp(−K
ai
t)). (3.25)
In general, we ca n write a model for c
i
(t) as
c
i
(t) = h(t, θ
i
) (3.26)
where θ
i
is a set of parameters spec ific ally for this subject. The parameters
may depend on factors such as age, body weight etc., hence one may write
θ
i
= X
i
θ + Z
i
v
i
(3.27)
where X
i
and Z
i
are factors including the intercept and θ are population
parameters. v
i
represents the remaining variability in θ
i
, after accounting for
those explained by factors ...