$Id: README_PluginDetails 1168 2009-09-29 09:53:15Z nicklas $
== Introduction ==
There are many plug-ins in the Illumina plug-in package for BASE. This
file gives detailed information on some of the contributed plug-ins.
== Illumina detection P-value calculation ==
This plug-in implements !BeadStudio like detection P-value calculations
for Illumina expression data (see
http://www.genomecenter.ucdavis.edu/expression_analysis/documents/illumina_normalization_081201.pdf)
on detection P-values.
The plug-in will ''always'' base the detection P-value calculation on
raw data values, ''i.e.'', the mean raw intensity for the different
signals. By default the calculations are based on negative controls
available in the root bioassay set for the current analysis
branch. The user may change this to only use negative controls in the
current bioassay set.
The detection P-value plug-in does not filter the assays, it provides
the detection P-values usable in a filter step after running this
plug-in.
=== Parameters ===
The plug-in requires input of array type since detection P-value are
calculated differently depending on array type.
Users may select to use negative controls in the current bioassay set
only. The default behaviour is to use all negative controls in the
root bioassay set for the current bioassay set.
A cut off parameter is available to exclude outliers within
the negative controls. The `cutoff` defines the acceptable negative
control signal range
{{{
median-MAD*cutoff < I < median+MAD*cutoff
}}}
where `MAD` is the median absolute deviation.
=== Implementation details ===
Each assay is treated separately, i.e., no samples are combined
together. All calculations are made on the raw bead-type level data,
i.e., on the average expression value for each bead type and raw data
is always used irrespective when in analysis the detection P-value is
calculated.
''Pvalue calculation for whole genome arrays:''
For all signals `i` calculate the detection P-value as
`Pvalue = 1-R/N` where `R` is the rank of the signal `i` relative to the
negative controls and `N` is the number of negative controls.
''Pvalue calculation for others array types (DASL, miRNA, !VeraCode
DASL, and Focused Arrays):''
For all signals `i` calculate the detection P-value as
`Pvalue = 1/2 - 1/2 * erf( [i-AvgControl]/StdControl/sqrt(2) )` where
`AvgControl` is the average intensity of the negative controls,
`StdControl` is the standard deviation of the the negative controls,
and `erf` is the error function
(http://mathworld.wolfram.com/Erf.html). The error function is used
for arguments within the range (-4,4). To save CPU cycles, the function
value for arguments outside this range is set to -1 and 1,
respectively.
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{{{
Copyright (C) 2009 Jari Häkkinen
This file is part of Illumina plug-in package for BASE.
Available at http://baseplugins.thep.lu.se/
BASE main site: http://base.thep.lu.se/
This is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.
The software is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with BASE. If not, see .
}}}
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