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\name{get.conservative.fold.enrichment.profile}
\alias{get.conservative.fold.enrichment.profile}
%- Also NEED an '\alias' for EACH other topic documented here.
\title{ Estimate minimal fold enrichment/depletion along the chromosomes }
\description{
The method provides a statistical assessment of enrichment/depletion
along the chromosomes. To assess tag density enrichment/depletion, a
sliding window of a specified size (\code{fws}) is used to calculate
the density of the foreground tags (\code{ftl}). Multiple, typically
larger windows are used to estimate background tag (\code{btl}) density around the
same location. The densities are compared as ratios of two Poisson
processes to estimate lower bound of foreground enrichment, or upper
bound of foreground depletion. If multiple window sizes were used to
estimate the background tag density, the most conservative one is
chosen for each point.
}
\usage{
get.conservative.fold.enrichment.profile(ftl,
btl,
fws,
bwsl = c(1, 5, 25, 50) * fws,
step = 50,
tag.shift = 146/2,
alpha = 0.05,
use.most.informative.scale = F,
quick.calculation = T,
background.density.scaling = T,
bg.weight = NULL,
posl= NULL,
return.mle = F)
}
%- maybe also 'usage' for other objects documented here.
\arguments{
\item{ftl}{ foreground tag vector list }
\item{btl}{ background tag vector list }
\item{fws}{ foreground window size }
\item{bwsl}{ background window scales. The size(s) of background windows
will be \code{fws*bwsl}. }
\item{step}{ spacing between positions at which the
enrichment/depletion is evaluated }
\item{tag.shift}{ number of basepairs by which positive and negative
tag coordinates should be shifted towards eachother (half of binding
peak separation distance)}
\item{alpha}{ desired level of statistical significance }
\item{use.most.informative.scale}{ for each position, instead of
evaluating enrichment ratio bounds for all background window scales,
choose the one with the highest observed density to speed up the calculations}
\item{quick.calculation}{ Use square root transformation method
instead of a Bayesian method. This speeds up the caclulation
considerably and is turned on by default. }
\item{background.density.scaling}{ If TRUE, regions of significant tag
enrichment will be masked out when calculating size ratio of the
signal to control datasets (to estimate ratio of the background tag
density). If FALSE, the dataset ratio will be equal to the ratio of
the number of tags in each dataset.}
\item{bg.weight}{ optional weight by which the background density
should be multipled for scaling. If not supplied, the weight is
calculated based on the ratio of the reduced ChIP to input dataset sizes. }
\item{posl}{posl}
\item{return.mle}{return.mle}
}
\value{
A list of elements corresponding to chromosomes, with each element
being an $x/$y data.frame giving the position and the log2
conservative estimate of enrichment/depletion fold ratios around that
position.
Use \code{\link{writewig}} to output the structure to a WIG
file.
}
\references{ R.M.Price, D.G. Bonett "Estimating the ratio fo two Poisson
rates", Comp. Stat & Data Anal. 32(2000) 345}
\seealso{ \code{\link{get.smoothed.tag.density}} }
\examples{
\dontrun{
enrichment.estimates <- get.conservative.fold.enrichment.profile(chip.data,
input.data,
fws=2*binding.characteristics$whs,
step=100,
alpha=0.01);
writewig(enrichment.estimates,
"example.enrichment.estimates.wig",
"Example conservative fold-enrichment/depletion estimates shown on log2 scale");
}
}
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