STANDARD DEVIATION
Standard deviation is a way of measuring how much variation there is in a set of data.
Variation
is an expected part of biology.
With any set of values, it is unreasonable to expect that all the
numbers will be equal: there will most often be some deviation from the expected or average
value.
Some systems, such as rainfall in different states of the union, display a wider variation,
while other systems, such as the number of leaves on a clover stalk, display a smaller variation.
By standard deviation, the diversity of a population can be quickly communicated.
Standard
deviation is also an important tool for determining relationships among different populations.
Calculation of Standard Deviation
Shown to the right is the formula to calculate the standard
deviation.
The variables stand for the following factors:
s = standard deviation
n = sample size
m = arithematic mean
y = an original data point
Σ
= stands for the sum value of all the data points minus the mean squared.
Follow the steps below to find the standard deviation for the data set: 4, 7, 5, 3, 6.
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 Fall '07
 Macedone
 Standard Deviation

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