Frequency Polygon
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Transcript of Frequency Polygon
Frequency Polygon
Frequency Polygon A frequency polygon is a line graph in
which points are joined by straight lines and closed to make a polygon
A frequency Polygon indicates the spread and skewness of distribution.
Drawing Frequency Polygon A frequency polygon is drawn by
plotting the frequency (or frequency density) against the midpoints of the data.
It can be superimposed on a histogram by connecting consecutive midpoints of the tops of columns
The area under the polygon represents the frequency of the data ( and is the same as the area of all the bars in the histogram)
Example 1
Example 1
Example 1
Example 2
Example 2
Drawing Frequency Polygon More Examples for you to try:
Analyzing Frequency Polygon When the sample is large and there is a large
number of intervals, since there are a large number of line segments the frequency polygon approaches FREQUENCY CURVE.
The Frequency Curve (or the Polygon) indicates the spread/dispersion of the distribution.
Low Dispersion
High Dispersion
Analyzing Frequency Polygon A Frequency Curve (or the Polygon) also
indicates the SKEWNESS (“lopsidedness”) of the distribution.
Normal Curve (symmetric)
Examples Weight, Height, IQ Test scores
Analyzing Frequency Polygon A Frequency Curve (or the Polygon) also
indicates the SKEWNESS (“lopsidedness”) of the distribution.
Positively Skewed Distribution
Examples Number of children in a family Age at which women marry Distribution of wages in a firm
Positive side stretched
Analyzing Frequency Polygon A Frequency Curve (or the Polygon) also
indicates the SKEWNESS (“lopsidedness”) of the distribution.
Negatively Skewed Distribution
Examples Daily maximum temperatures for a month in summer Reaction times for a experiment
Negative side stretched