Z-score
The z-score is the z-transformed PBM-determined median probe fluorescence value (f) for each kB site.
The z-transformation is based on the mean (u) and standard deviation (s) of the median probe fluorescence values (f) for the 1200 randomly selected 10-bp sites (i.e., the background distribution).
z = (f - u)/s
Fig 1b from Siggers & Chang (submitted) showing the distibution of 3,285 kB z-scores (black) and 1,200 background z-scores for the RelA:p50 experiment. The position (z-score) for a set of known kB sites is shown.