This method assumes that the red and green
intensities are related by a constant factor, i.e
. After
the normalisation the centre of the log ratio distribution is
therefore shifted to zero,
A common choice for
is the median of the M values for a particular
gene set [7]. This procedure is not commonly used, since the
red and green intensities often do not follow this relation [4].
Bjørn Kåre Alsberg
2006-04-06