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Find the Mean
(Average) to determine a number that is representative of the health status during this 5
year period.
Add the numbers and divide by 5.
Look at Health People 2010 to determine a goal or standard.
This method is based on the fact that most health data moves in a straight line over time,
especially over a 5 year period. Even though the data may vary over 5 years, it moves in a
straight line trend. Health data may often jump up in one year, only to go back to its
historical trend the next.
It is usually meaningless to analyze data where less than 20 events occur over the study
period. An event is a death, an occurrence of a disease, etc. This is called the 'problem
of small numbers'. If you have very few events, a change of one or two can have a big
impact of the rate, and can lead to unjustified conclusions. For example. If 100 people
die from diabetes in your community each year, 2 more dieing is only a 2 % change, which
is not a big deal. If you have 10 people die of diabetes and then 2 more die, this is a
20% change, and could lead to the conclusion that there
is a diabetes 'epidemic'. This data is meaningless. People in a community often express
concern to health officials because of an outbreak of a disease in their community; this
usually involves small numbers of diseases and normal variations. Using 5 years of data
will usually eliminate the 'problem of small numbers'. For more information see:
http://www.health.state.pa.us/stats/techassist/flow1a.htm
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