Importance of Accuracy and Precision.
Importance of Accuracy and Precision.
Importance of Accuracy and Precision.
precision.
On Friday the 13th of June, our class had an experiment to practically see the
difference between accuracy and precision. Students from each group tried to
throw chalk pieces into the bulls eye. Later each groups throws were analysed
to see who was accurate and who was precise.
Were bombarded with numbers every day. But seeing a number
and understanding it are two different things. Far too often, the true
significance of a figure is hidden, unknown, or misjudged. There is an
important distinction between accuracy and precision.
Here is one example reported cases of cholera worldwide. Cholera is perhaps
the most widespread and serious water-related disease, directly associated with
the failure to provide safe drinking water and adequate sanitation. Billions of
people lack this basic human right and suffer from illness as a result. Millions die
unnecessary deaths.
The World Health Organization has reported that in 2011, 58 countries
reported 589,854 cases of cholera.
Now what does this number mean? Is it accurate? Is it precise?
Accuracy and precision are not the same things. In the field of science and data,
accuracy is typically considered to be a measure of how close a number is to
that quantitys true value. Precision is a term which describes the degree to
which repeated efforts to do, or measure, something will produce the same
results. Any particular data can be accurate, precise, both, or neither.
So, back to cholera. This number of cases 589,854 seems very precise. It is
reported to six significant figures a very high degree of precision.
In fact, however, this number is an example of false precision it is presented
in a way (with six significant figures) that implies, incorrectly, a higher degree of
both precision and accuracy than reality warrants.
Why? First, it is entirely possible that this number is exactly the sum (i.e., it is
precise) of the number of cases of cholera reported to WHO by the 58 reporting
countries. But experts on water-related disease note the following:
1. Many countries around the world do not report water-related diseases at
all. As noted above, in 2011 only 58 countries reported cholera. We know
cholera occurred in countries not reporting.
2. Most cholera outbreaks are not detected. Thus, even countries reporting
cholera underreport.
3. There is no agreed-upon standard definition for determining if a case of
extreme or acute watery diarrhea is cholera or a different illness that
presents the same way.
4. Health surveillance systems (i.e., medical systems for tracking, recording,
and reporting disease) vary dramatically from country to country in their
quality and completeness.