I have not RTFS, but I am pretty good with probabilities and statistics.

I doubt the answer is "1-(pConnectFailed+pSearchFailed)" because that might produce negative probabilities. Suppose both are 2/3.

The following might justify the code as-is:

If pNotConnectFailedOrSearchFailed is an estimate of "the probablity that neither the connection *nor* the search will fail" then it is the same estimate as "the probablity that the connection and the search will succeed".

Let C be a r.v. equal to 1 if connection succeeds, 0 if fails
Let S be a r.v. equal to 1 if search succeeds, 0 if fails

Then Prob(C and S)=Prob(C)*Prob(S given C)

Obviously, Prob(C)=1-pConnectFailed.

Now the crucial question: Does pSearchFailed just estimate "the probability that the search will fail given the connection succeeded"? If not, someone please tell me what it means! If so, then Prob(S given C)=1-pSearchFailed. In which case, the code is correct as is.

And if all of the above is correct, I suggest renaming pNotConnectFailedOrSearchFailed to pConnectAndSearchSucceeds.

-Martin

Ian Clarke wrote:
Line 160:

                double pNotConnectFailedOrSearchFailed =
                        (1 - pConnectFailed) * (1- pSearchFailed);

My high-school math is a bit rusty, but shouldn't that be:

... = 1-(pConnectFailed+pSearchFailed);



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