how to estimate r-factor

I've been making up some simulation using ns (network simulator), using
five different codecs (g711a, g711u, gsm, ilbc, spx) to simulate
different voip traffic and I need to estimate r-factor for these
simulations from the parameters (delay, jitter and packet loss) I've
got from the simulation results.

Does anybody here know how to get the R-Factor parameters (R Factor =
Ro - Is - Id - Ie + A) from the data I've got from my simulation?

Thanks for helping.

Bruno Ricci

Bruno Ricci