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December 18, 2009
What is Normal?

 
 


I have a hard time these days listening to the news (and don’t even get me started on "talk radio").  News is about reporting abnormal events that occurred during the day.  (It is also about discussing lives of well-known people....but I’ll leave that topic for another day)

We also hear a lot about statistics in the news.  The jobless rate is over 10%...the housing starts in October in Northern Illinois were 21.1% better than they were in September...67.2% of children under the age of 5 believe in Santa Claus...

Statistics is a branch of mathematics that concerns itself with the science of probability.  The main focus of statistics is the "normal bell-shaped" distribution curve that can be used to predict probability of events occurring.

Bell Curve

The first step in using a "bell-shaped" curve is to calculate the average or mean.  This is done by adding up all of the data of a sample and then dividing by the total number of samples used.

For example, take the following sample of numbers :

40, 40, 48, 61, 72, 81, 85, 83, 78, 57, 45, 42

The average of these number is the sum of them or 732 divided by the total amount of number, in this case 12 and we get an average (or mean) of 61

We also hear a lot about the median.  The median is a number where half of the data points are above and half are below based on ranking.  Ranking the above numbers we get:

40, 40, 42, 45, 48, 57, 61, 72, 78, 81, 83, 85

In this case the median is the half-way point between 57 and 61 or 59.

The exercise above was used to illustrate a point. 

Those numbers actually represent the average monthly temperatures in New York City over a year.  So if you were to ask me what the temperature in NYC was...I might tell you "on average" it’s 61° F, or perhaps the median temperature of 59° F both of which more than likely, are wrong on any given day in NYC...

Statistics without context are meaningless in most uncontrolled situations.  Even when there is context, statistics can only describe a probabilistic "normal" outcomes.  Should I bring just a light jacket with me to NYC in January knowing that the average temperature there is 61°?

We create expectations using statistical probability each day of our lives.  We may expect the newspaper to be on our front porch when we wake up, highway traffic to be lighter on a Saturday morning than on a weekday morning, or that our favorite dish might be on the menu at a new restaurant.

Although we instinctively know that there is a chance that the desired results will not occur, failure to meet expectations can cause stress, anger, discomfort, angst and/or fear in us.

We, as people, want predictability in our lives.  We need to experience cause and effect relationships.  We require order...but then probability strikes...

Bad things do happen to good people and vice versa...young and seemingly healthy people die from natural causes...people win the lottery...a snow storm can hit NYC in July...freak occurrences...outliers of statistical probability...but they do happen...and that’s what’s reported to us...

The use of statistics is overrated and mostly reported in the media without context. 

Mark Twain once said that the are three types of reporting:  Lies, Damn Lies and Statistics...

What is normal?...I don’t really know...but even if I did...I’m only right 48.8% of the time...

Thank you very much for all your support of OptiFuse as we try to fit more people under our curve...



Jim Kalb
President
OptiFuse
jimk@optifuse.com

 
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