Conditioned averages in chemical kinetics

It is argued that the molecular population functions which satisfy the deterministic reaction‐rate equations, and the first moments of the solution to the stochastic master equation, can be generally regarded as differently conditioned averages of the same random variables. Although these two kinds of averages usually differ only on the microscopic scale, it is pointed out they can differ macroscopically for chemical oscillators. However, this is not a sign of any inconsistency in the theory because it is fully explained by the different conditionings employed. Both kinds of averages are seen to play legitimate, useful roles in describing the dynamics of a stochastically evolving chemical system.