Median

${\mathrm{log}\phantom{\rule{0.5em}{0ex}}}_{2}\left({x}_{j}^{i}/{\tilde{x}}_{j}\right)$

Where ${x}_{j}^{i}$ is the value for probe i on array j and ${\tilde{x}}_{j}$ is the median value for all probes on array j

Control

${\mathrm{log}\phantom{\rule{0.5em}{0ex}}}_{2}\left({x}_{j}^{i}/{\overline{c}}_{j}\right)$

Where ${x}_{j}^{i}$ is the value for probe i on array j and ${\overline{c}}_{j}$ is the mean value for control oligo c on array j

Array

${\mathrm{log}\phantom{\rule{0.5em}{0ex}}}_{2}\left({x}_{j}^{i}/{x}_{c}^{i}\right)$

Where ${x}_{j}^{i}$ is the value for probe i on array j and ${x}_{c}^{i}$ is the value for probe i on control array/channel c
