Cows or Sharks? Which are more likely to kill you?

Give me a minute, and I'll get to the cows and sharks.

You would be surprised at how few doctors are familiar with even the most basic statistics. Medical journal articles often have statistical errors which are missed by manuscript peer reviewers and readers alike.

Most medical students have taken a course in statistics, but it is usually taught in the first or second year of school. By the time they start residency training when they could really use the information, they have forgotten most of it. Statistics should be taught during the clinical years of medical school and reinforced throughout residency training.

Hospital administrators are even more clueless than physicians. I have blogged before (here and here) about the irrational responses of administrators to miniscule changes in poorly constructed surveys of patient satisfaction. When scores go down by insignificant percentages, all hell breaks loose with task forces, ad hoc committees and browbeating of staff.

Here’s a fun exercise involving statistics. It's OK. No formulas will be discussed.

Which animal kills more people per year in the United States, cows or great white sharks?

Although not long ago a German tourist was killed by a shark in Hawaiian waters, the answer is overwhelmingly "cows."

How can this be? You rarely hear about a cow killing a human but it happens about 20 times every year. Between 2003 and 2008, 108 people died from injuries caused by cattle across the United States, according to the Centers for Disease Control and Prevention. That's 27 times the whopping 4 people killed in shark attacks in the United States during the same time period, according to the International Shark Attack File.

Guess how many cows there are in the US.

According to the Drovers Cattle Network, there were 96.5 million head of cattle here as of mid-2013. The cattle population dwarfs the number of great white sharks. The New Ecologist estimates that the number of great whites in the entire world is about 3500.

The Guardian recently reported that there have been 1,085 recorded shark attacks in the US since the year 1670 for an average of only 3.5 shark attacks each year for the last 342 years.

Although not as dramatic or as newsworthy as a shark attack, it is far more likely that a person will be killed by a cow than a shark.

So keep your statistical radar turned on. Be skeptical.

And if you see an udder in the water, get to shore as fast as you can.