Figure 2
The pvalue distance. Left: Often is the case that the distance between two measurements depends not only on the relative nominal difference between the measurements but also on the absolute magnitude of the each one of the measurements. For example, two measurements z1 and 
are statistically more similar to each other than the two measurements z2 and 
. That is to say that there are fewer measurements with score as high as z1 and and therefore fewer instances that have similar properties. The measurements in our case are the zscores that indicate the significance of the match between a sequence and a structural template (the source). For a given zscore z, the pvalue measure pvalue(z) is an estimate of the total probability mass in the protein sequence space of sequences that match the structural template with zscore ≥ z. Right: The least significant pvalue of the two associated with the two measurements is an estimate of the mass of sequences with similar properties (note pvalue 1 <pvalue 2).