This function performs the moving window chi-square calculation. It
is written in C, so is quite fast.
Usage
do.aGFF.calc(x, window, thresh)
Arguments
x
An aGFF class object
window
An integer value, representing the number of basepairs
to include in the windowed chi-square calculation
thresh
The quantile of the data distribution for each sample
that will be used to classify a probe as positive
Value
An object of class aGFFCalc
Details
A window size on the order of 2-3 times the average size of fragments
from sonication, digestion, etc. and containing at least 8-10 probes
is the recommended size. Larger size windows are probably more
sensitive, but obviously reduce the accuracy with which boundaries of
signal can be called.
A threshold of between 0.9 and 0.99 seems empirically to be adequate.
If one plots the histogram of data values and there is an obvious
better choice (such as a bimodal distribution, with one peak
representing enrichment), a more data-driven approach may yield better
results.