I suspect this is a misleading statistic.

While on the surface it sounds like apples to apples, it really isn't.

Basically, if a bear shows up, there is little reason NOT to deploy the bear spray. If the bear goes away, the spray worked, right?

Consider that in many situations the bear is checking you out. It isn't really committed to an attack. It may bluff charge you, see you aren't a threat, and wander off.

So... It many of these cases option 3: doing nothing probably has similar results to deploying the bear spray.

That said, the bear spray is clearly a deterrent. Basically it puts the human on similar ground as a skunk. Bear approaches, fog of unpleasantness appears. Yuk.

The gotcha is if the bear is committed to the attack (has cubs for example), I suspect the effectiveness of bear spray is near zero.

So as a deterrent, I suspect bear spray is good. Better than doing nothing, and better than a firearm.

But, if the bear is committed, the effectiveness of the firearm is probably going to be by far your most effective option.

Of course, "by far most effective" isn't going to be "highly effective".

These are two things that should be used together, not compared. One is a deterrent, one is your last ditch defense. These should be layered with the forethought to try to avoid startling the bear in the first place.

-john