**AP
Physics
Brockport High School NY USA
Science **

Introduction

**Statistical
Terms**

*mean
*- the average of all data collected.

*median*
- the middle measurement in a set of data.

*mode*
- the most frequently occurring measurement.

*range*
- the difference between the highest and lowest measurement.

*dispersion*
- a measure of "clustering@
of data points around the center.

**Determining
dispersion**

1.
**Mean deviation**
is the average deviation from the mean.
It is a weak indicator of dispersion and is seldom used
in statistics. It can be used to compare dispersion in two or
more experiments.

2. ** Variance**
is the average **sum of
the squares of the deviations** from the mean.
It is designated by the lower case Greek letter sigma, **s ^{2}**,
and is used to calculate the more popular statistic called
standard deviation. To
find

3.

68% of measurements fall within "1
s
of the mean

95%
fall within "2 s
of the mean

99.73%
fall within "3 s
of the mean

**Example:**

The following are
heights (in meters) of 11 students at Brockport High School:

1.70
1.85
1.65
1.60
1.35
1.55
1.60
1.40
1.80
1.75
1.60

Find the **mean**.
_________m

Find the **range**.
_________m

Find the** median**.
_________m

What is the **mode**?
_________m

Calculate the **variance **(s^{2}).
[(1.70 - mean)^{2} + (1.85 - mean)^{2 }+
...] / (11 -1)

Calculate the **standard deviation** (s)
by taking the square root of the variance.

Determine the range of
heights that will include 68% of all seniors, and 95% of all
seniors.

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