GetAlpha {GeneSelector} | R Documentation |
Both GetStabilityLm and GetStabilityOverlap
depend on a parameter alpha
if decay=exponential
.
If the weights are based on ranks, then a nonlinear regression
of the form
pval = 1- exp(-alpha*rank)
can be used to find an appropriate value for alpha
via nonlinear least squares. In order to adjust for too
'optimistic' p-values, multiple testing adjustments should
be used, s. AdjustPvalues.
GetAlpha(ranking, pval, alpha0 = 0.01)
ranking |
A numeric vector of ranks, regarded as regressor. |
pval |
A numeric vector of p-values corresponding to the vector
ranking . |
alpha0 |
A starting value for the nonlinear least squares estimation procedure passed to nls |
The nonlinear least squares estimator for alpha
, s.
description.
It is more or less equivalent to use a p-value based ranking instead of ranks combined with this procedure.
Martin Slawski martin.slawski@campus.lmu.de
Anne-Laure Boulesteix http://www.slcmsr.net/boulesteix
GetStabilityLm, GetStabilityOverlap, AdjustPvalues, nls
### rankings ranks <- 1:100 ### corresponding p-values pvals <- 1-exp(-0.01*ranks) + rnorm(100, sd=0.001) ### determine alpha alphaopt <- GetAlpha(ranks, pvals, alpha0 = 0.01)