Species identification in the HSR model using logistic regression.

A “+” indicates that the estimated coefficients are significant and positive. The symbol ✓ denotes correct identification of the corresponding reaction. In Case 2, the absence of natural P2 production () creates an identifiability issue, as the reference reaction shares its sole reactant P1 and reaction rates with two other reactions. This makes the reaction types indistinguishable from P1 alone and is reflected by the blanks in rows 1 and 7 of the table, which correspond to reactions involving P1.