Probability of a shark attack - a statistical fallacy?

[wonbok]

Although it may comfort me as I jump into water to think that the likelihood of being attacked by a shark is lower than being hit by a lightening, I cannot stop thinking it's a crooked comparison and wondering what are the real chances of being attacked by a shark.

As far as I know, the shark-vs-lightening comparison comes from the mere number of fatalities per year caused by shark attacks vs. lightening. I'm no statistical expert, but this cannot be a fair comparison, as you stand absolutely no chance of being attacked by a shark if you stay away from the water, whereas virtually everyone stands a chance (except for those living in an area where lightening never takes place) of being hit by a lightening.

Therefore, I think the actual probability of a shark attack should be based on those who assume the risk - those who dive in areas where sharks are known to make appearance. Again, I would need help from a statistical wiz, but shouldn't the probability be something like the number of fatalities (or injuries) per year divided by the aggregate number of diving hours spent per year by the divers worldwide in shark-appearing areas, thus the result being something like 0.00** percent per each hour you spend under water in a shark-appearing area? Of course, I'm not assuming there would be readily available data on the amount of time the divers spend each year worldwide, but isn't that also part of statistics - making a reasonable assumption?

Has there been an effort to come up with this kind of numbers? Whatever the result, it will not stop me from making my next diving trip, but I want to put things in perspective and see what are the real odds that I'm facing.

 

[BlueDevil]

and what are the real chances of being attacked by a shark.

However you do the stats the risk of getting attacked by a shark is incredibly small. It will of course vary with different regions, in relation to the species to be found and the number of sharks likely to be in the area. I think any realistic statistic would probably be almost impossible to calculate. Unless you are doing a high risk activity, such as diving at a seal colony during breeding season the risk is so small it is probably pointless to even consider it.

As far as I know, the shark-vs-lightening comparison comes from the mere number of fatalities per year caused by shark attacks vs. lightening. I'm no statistical expert, but this cannot be a fair comparison, as you stand absolutely no chance of being attacked by a shark if you stay away from the water, whereas virtually everyone stands a chance (except for those living in an area where lightening never takes place) of being hit by a lightening.

This is similar to the argument that you are never going to die whilst flying if you never get in a plane. It is of course true...if you never go near a body of water you are not going to get attacked by a shark. But think of the enormous restrictions you would place on your life if you avoided going in planes, going in water, and a host of other activities. I couldn't say there have never been times when the thought of sharks has not bothered me while diving in some high risk areas, but generally the likelihood of an attack is so small that we should not let it disturb our enjoyment of our diving.


BD

PS Just another thought...the risk of shark attack is often said to be less than the risk of dying from a bee sting. Of course unless you happen to have a severe allergy to bee stings you are not going to die from a bee sting so it is a fairly useless statistic (unless you get stung by thousands of them at once)

 

[Cudabait]

Although it may comfort me as I jump into water to think that the likelihood of being attacked by a shark is lower than being hit by a lightening, I cannot stop wondering it's a crooked comparison and what are the real chances of being attacked by a shark.

As far as I know, the shark-vs-lightening comparison comes from the mere number of fatalities per year caused by shark attacks vs. lightening. I'm no statistical expert, but this cannot be a fair comparison, as you stand absolutely no chance of being attacked by a shark if you stay away from the water, whereas virtually everyone stands a chance (except for those living in an area where lightening never takes place) of being hit by a lightening.

Therefore, I think the actual probability of a shark attack should be based on those who assume the risk - those who dive in areas where sharks are known to make appearance. Again, I would need help from a statistical wiz, but shouldn't the probability be something like the number of fatalities (or injuries) per year divided by the aggregate number of diving hours spent per year by the divers worldwide in shark-appearing areas, thus the result being something like 0.00** percent per each hour you spend under water in a shark-appearing area? Of course, I'm not assuming there would be readily available data on the amount of time the divers spend each year worldwide, but isn't that also part of statistics - making a reasonable assumption?

Has there been an effort to come up with this kind of numbers? Whatever the result, it will not stop me from making my next diving trip, but I want to put things in perspective and see what are the real odds that I'm facing.

Wonbok,

It's a good thought. However, a compilation of total diver's hours worldwide would be almost impossible to obtain.

Yes, there has been a significant effort to categorize information by available statistics regarding shark attacks. You might try www.flmnh.ufl.edu/fish/sharks/isaf/isaf.htm.

I, personally, would like to see something along these lines established regarding barracuda attacks. To date there is none.

Regards,

 

[Hoppy]

I cannot stop wondering it's a crooked comparison and what are the real chances of being attacked by a shark.
snipped

but I want to put things in perspective and see what are the real odds that I'm facing.

Do you put into perspective the risks you take in driving to the dive site ?

Damned sight more chance being dead from that activity.

Why sweat the shark attack ?

 

[Gary D.]

Sharks have a bad rep that Hollywood has helped develop. It doesn't matter where you are people are afraid of sharks. Here’s proof.

Several years ago some friends of mine suited up with shark fins on our backs and swam back and forth just outside a local swim area.

Lifeguards started screaming for everyone to get out of the water as they call the police department. When the police showed up they actually got into the water to pull people out.

Nobody noticed the divers bubbles or brightly colored tanks on their backs. All they saw was sharks.

Might be the right thing to do in some areas but we are 300 miles from Puget Sound and 400 miles from the ocean. With the amount of non-passable dams on the river Salmon can even make it back.

(Originally Posted by wonbok
and what are the real chances of being attacked by a shark.) A lot less, almost nil, if you don't look like a seal!

Gary D.

 

[Don Burke]

Although it may comfort me as I jump into water to think that the likelihood of being attacked by a shark is lower than being hit by a lightening, I cannot stop wondering it's a crooked comparison and what are the real chances of being attacked by a shark.

The recent history of shark attacks on the Virginia and North Carolina coasts tells me that your chances of getting attacked by a shark might just be zero unless you are swimming on the surface at dawn or dusk.

Those are the conditions for all of the attacks in recent years.

I've had sandtigers and bulls get curious, but no aggression was shown.

 

[Kim]

The recent history of shark attacks on the Virginia and North Carolina coasts tells me that your chances of getting attacked by a shark might just be zero unless you are swimming on the surface at dawn or dusk.

Those are the conditions for all of the attacks in recent years.

I've had sandtigers and bulls get curious, but no aggression was shown.

Considering that most shark attacks occur at the surface - and in the surf zone - rather than base a statistic on how many diving hours per shark attack, it would probably be fairer to base such a statistic on how many hours people swim in the sea!
As far as the lightning stat goes - how many of them were golfers?
Lastly - Gary D - I think you and your friends were totally mean, scaring everybody like that!!

 

[Don Burke]

Considering that most shark attacks occur at the surface - and in the surf zone - rather than base a statistic on how many diving hours per shark attack, it would probably be fairer to base such a statistic on how many hours people swim in the sea!

The whole thing gets pretty difficult, actually.

In television broadcasting, the definition of "viewer" causes the same problems. I know people who have the set running whenever they are in the house. Are they "viewers"? Can meaningful information be derived from what program an unattended set is showing?

Is someone walking across I-5 in Los Angeles a "pedestrian"? Is someone walking across I-8 in New Mexico a "pedestrian"? Does that mean they should be in the same category for safety statistics?

Is someone ankle deep in the foam "swimming"? If not, how far out do they have to go to be "swimming"?

Should someone swimming at dusk around baby seals be in the same category as someone swimming off Hanauma Bay at high noon?

The shark attack numbers are so small they don't lend themselves to PowerPoint charts. The lightning strike numbers have the same problem.

I prefer to deal with the incidents and work backwards from there, otherwise the statistics are misleading.

I would imagine that ages between 5 and 75 would show higher incidents of shark attack. It wouldn't mean anything since there are too many confounding variables at work.

Broad strokes just won't paint this picture properly.

 

[Mako Mark]

my policy is:


DONT ATTACK SHARKS!!!!

and Im sticking with it.

 

[pipedope]

Lies,
D**n Lies
Statistics

The problem is how you do the calculations and the source data.

I have never had a dangerous shark encounter in something like 1500 hours on scuba in the ocean. I have never had a dangerous aligator encounter in hundreds of days of working in the water in FL.
I HAVE been hit by lightning.

Should divers be concerned about sharks?
YES, mostly for the sharks safety. Shark populations are dropping but human numbers are up.
If you dive with sharks, especially if you are right in the midst of large concentrations of sharks then your risk is higher. Are you a shark researcher? If not then the risk of shark attack is very low.

BTW I buy lottery tickets. Now and then I buy one quick pick for the FL lotto. By doing that I take my chance of winning from NONE to extreemly slight.