Figure 2.

Defining local distance measures between probability profiles. For the validity of the methodology and an unambiguous interpretation of its results, it is essential to proceed hierarchically, and to compare distributions obtained from restricted groups of data, respectively in conditions B∧C₁ and B∧C₂, to the distribution obtained in the common biological condition B (pooled data). Each comparison is based on the computation of the Kullback-Leibler divergence $D_n^{(X)}(B\wedge C_i|B)$ between the distributions $P_n^{(X|B\wedge C_i)}$ and $P_n^{(X|B)}$. The significance of the comparison result depends on the variability of the distribution described by the functional distribution $P_{P_n}^{(X|B\wedge C_i)}$.