Transcript Standard Deviation!

Standard Deviation!
By Rahshad Cobb
Sardai Payne
Charish Marshall
Chevez Whittaker
What is Standard Deviation?
Standard Deviation is the simple
measurement of the dispersion of data.
 A “Low” Standard Deviation means that
all the data points are closer to the
mean.
 A “high” Standard Deviation means that
all data points are more spread out over
a large range of values.

How does it work?

To find the Standard Deviation you
must:
Find the mean of the data set.
 Find the Standard Deviation of each
number from the mean. (Data # - Mean)
 Square each of the Deviations
(Data # - Mean)²
 Find the mean of these Deviations
 Find the square root to get the final
answer

What?
Well
if you didn’t
understand that
explanation, here is an
example…
Lets Suppose…
 Lets
suppose you wanted to find
the standard Deviation of the
following data set:

3, 7, 7, and 19
Step 1: Find the Mean

First, find the mean (Average) of the
data set.

As you can see, the mean is 9
Step 2: Subtract the mean from
each data point.


Just subtract the mean (9) from each
of the Data points (3,7,7,19)
The answers are {-6,-2,-2,-10}
Step 3: Square each deviation

Square each of the deviations.

The answers are {36,4,4,100}
Step 4: Find the mean
(Again…)


Find the mean of these deviations once
more!
The Answer is 36
Step 5: Final answer!


Find the Non-negative square root of
the mean.
The standard deviation for the data set
{3,7,7,19} is 6!