Finn and CureOrBust,
It seems to me that we are solving for very different numbers. One is the cumulative effect of the compounds, the second is the relative effect of Campath alone.
I agree that one cannot come up with a number of Campath acting alone. I.e., it was not tested this way.
The only way to support finn’s calculation, would be to assume independence of effects of the two targets. However, there, one would need to start with a cumulative effectiveness for both, not the relative effectiveness of both vs’ Rebif alone. I.e., if we know that the first target is 30% effective and the second is 80% or 88% effective with respect to the first alone. (See CureOrBusts calc, as I see it as more explanatory than mine.) Then, we can come up with the cumulative number.
Finally, assuming independence and now using the cumulative effectiveness, one can use finn’s calculation to attempt to estimate effectiveness of Campath alone.