Monday, April 18, 2011

“There are 3 kinds of lies: lies, damned lies, and statistics.”

“There are 3 kinds of lies: lies, damned lies, and statistics.”
                                                                        - Benjamin Disraeli

I'm sure at one point or another you've heard how statisticians can wield statistics to their will and make them say anything.  This is true.  However, all people need to know how to spot truthful statistics, and how to spot those that have been manipulated.
Dishonest statistics was the topic of conversation one evening when a good friend and firefighter was in town visiting from New Zealand.  He mentioned how he read a study about how dangerous firefighting was.  However, the way they portrayed the statistics in the study was misleading.  Yes, firefighting is a dangerous endeavor.  The question is, just how dangerous is it?  I looked up a few statistics in the US to examine this.

In 2008 there were 1,148,850 firefighters.  Of these, 79,804 (7%) were killed or injured in 2008 due to firefighting.  

A first thought upon reading this may be, "Wow, if I become a firefighter there is a 7% chance I will die . . ." This is simply not true.  On its own, this statistic is misleading.  Before you go conducting analyses to predict whether or not your firefighting days will result in survival, let's examine this statistic in a bit more detail. 

First, the idea of "killed or injured" stands out to me.  There is a big difference between the two.  Let's examine this a little further and separate the deaths from the injuries.  Of those 79,804 who were killed or injured, only 104 of them were killed, and 79,700 were injured. This corresponds to less than 1 out of 10,000 (1/100th of a percent) who were killed on the job in 2008.  Are you rethinking your dreams of fighting fires now?

While we're here, let's just examine this one step further, for the sake of honesty.  Of those 104 who were killed, 42 of them were career firefighters, and 54 were volunteer. This corresponds to less than 4 out of 100,000 career firefighters who were killed on the job in 2008.  

Is firefighting dangerous? Of course it is! I'm not trying to demean the bravery and hard work of the many men and women who dedicate their lives to saving lives.  However, let's not make the numbers into something they're not. After all, we statisticians are not liars, we are wielders of truth.


1 comment:

  1. Another interesting convolution of firefighter morbidity and mortality.

    The IAFF (the Union) frequently hijacks the denominator when making inferences to the incidence of death, thereby inflating the dangers.

    Then, if you more closely examine the causes of death, heart disease- very much a disease of lifestyle- is the category that leads the list.

    So, statistically, this is a pretty safe job.

    Now, let’s examine injuries on the job.

    There’s a very self-serving reason to report every hangnail and splinter. It goes to cumulative trauma. The percentage of line-of-duty retirements due to orthopedic causes is pretty huge. Again, a lot of this is related to fitness. But, the economic benefits are clearly in the court of the disabled. Tax free-income for life.

    -POD III