No, misses aren't zeros. A miss has a probability too. A highly unlikely miss counts less against you than a sure thing that somehow misses.

The probability of a miss is 1 minus the probability of a hit, but that means that if chance is 0.25 and you miss it you would get a 0.75 score. Even if a miss was negative that wouldn't be right.

In scoring, a miss gets the chance of a hit as a score so missing a 0.25 probable gives you -0.25 score. That sounds right and a negative average means you're doing worse than chance.

It's all very confusing. I've asked Dr Jones if he's found a way to do it. I'll let you know what he says.

Roger