[pct-l] interesting facts

[Bob Bankhead]

As a Certified Quality Engineer, statistics are a huge part of my life. You have to be very careful when quoting or interpreting statistics.

Paul is correct when he says "These stats don't address the proportion of the population that's exposed to these various critters."  I submit that they don't have to, because that's not the information trying to be conveyed here. 

Your PROBABILITY (or chance) of dying (the event of interest here) varies according to the number of such creatures (causes) you could possibly encounter in your location. These stats as quoted are not probabilities. 

These stats are the RATIOS between two possible causes of death, adjusted to a numerator of one for purposes of clarity.

Example:

Assume 100 world-wide human deaths are caused by bears.
Assume 1700 world-wide deaths are caused by spiders

The total of all human deaths caused by a bear divided by the total human deaths caused by spiders is 100 / 1700 = 1/17 or written another way, 1:17 (read as "one to seventeen") or  simply "1 out of 17". This tells us that (world-wide) for every one human death caused by bears, seventeen hmuan deaths are caused by spiders. It does not address one's probability of even encountering either a bear or a spider, let alone dying from said encounter.

And so on. 

Wandering Bob

  ----- Original Message ----- 
  From: bluebrain at bluebrain.ca 
  To: pct-l at mailman.backcountry.net 
  Sent: Friday, December 01, 2006 11:53 AM
  Subject: Re: [pct-l] interesting facts



  Stats are tricky!  These are just raw numbers and don't speak to the
  proportion of the population that's exposed to these various critters.

  Bees are everywhere, all year round.  Most of us will get at least one bee
  stings over the course of our lives.  There are plenty of varieties of
  deadly snakes (four in the continental US) and some share habitat with
  humans.  There's no shortage of poison spiders around the world ...
  funnel-web, red-backs, brown recluse, black widow, to name a few that can
  kill humans.  Dogs are plentiful and live almost exclusively in human
  country.

  So, all in all, a large percentage of the human population is exposed to
  bees, snakes, spiders and dogs, while relatively few of us, comparatively
  speaking, spend time in bear country.

  There are also billions of these other creatures, while there are really
  very few bears, even when in bear country.

  Interesting stats for sure, but unfortunately not a good representation of
  relative risk.

  Still, good numbers to reassure friends and family when they express worry
  about trail safety.  ;-)

  Cheers,
  Paul

  > For every human death from a bear,
  > 17 people die from spiders bites
  > 25 people die from snake bites
  > 67 people die from dog attacks
  > 180 people die from bee stings.