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Figure 9 | Algorithms for Molecular Biology

Figure 9

From: "Hook"-calibration of GeneChip-microarrays: Theory and algorithm

Figure 9

Probe-density distribution of the hook-curve (part a), the log-intensity distributions of the PM- and MM-probes taken from the N-range of the hook (part b) and the distribution of the S/N-ratio showing the specific signal distribution for log(R+1) > 0 (part c). About 40% of the probe pairs are absent according to the break-criterion. The distributions of their corrected intensities (bars) are well approximated by Gaussian functions (lines) with slightly shifted centres μ and nearly equal widths, σ (part b). Part c rescales the total distribution by using the argument r = log(R+1). The fraction of absent probes refers to intersection with the ordinate at r = 0 (40%). 60% of the probes are consequently called present with specific signals r > 0. Their distribution follows an exponential decay for values r ≥ r' = 0.5 with the decay constant λr. In the intermediate range r' < r < 0 the signal is approximated by a constant (see Eq. (28)). The rescaling from Σ0hook to log(R+1) slightly increases the decay constant (compare part b and a).

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