DRshrink {cir} | R Documentation |
Shrinkage fix to bias in observed rates under adaptive dose-finding design
Description
Adaptive dose-finding designs induce a bias on observed rates,
away from the target dose. This is well-known in other adaptive-design fields,
but has been overlooked by the dose-finding research community.
Flournoy and Oron (2020) examine the bias in the dose-finding context,
and suggest a simple shrinkage fix that reduces both bias and variance.
The fix is analogous to the empirical-logit fix to binary data,
but instead of adding 0.5 to each cell, target
is added to the 1's at each dose,
and 1-target
to the 0's.
The shrinkage is applied to the raw observation, so CIR or IR are carried out
on the shrunk data.
Usage
DRshrink(y, x = NULL, wt0 = NULL, target, swt = 1, nmin = 2, ...)
Arguments
y |
can be either of the following: y values (response rates), a 2-column matrix with positive/negative response counts by dose, a |
x |
dose levels (if not included in y). |
wt0 |
weights (if not included in y). |
target |
the balance point (between 0 and 1) around which the design concentrates allocations. |
swt |
the weight of the shrinkage. Default 1 (a single observation) |
nmin |
the minimum n at each dose, for the shrinkage to be applied. Default 2. |
... |
parameters passed on to |
Author(s)
Assaf P. Oron <assaf.oron.at.gmail.com>
References
Flournoy N and Oron AP, 2020. Bias Induced by Adaptive Dose-Finding Designs. Journal of Applied Statistics 47, 2431-2442.