- What is a frequency polygon?
- Characteristics of the frequency polygon
- What is a frequency polygon for?
- How to make a frequency polygon?
- Examples of frequency polygons
- Frequency polygon in Excel
We explain what a frequency polygon is in statistics, what it is for and how to do it from a histogram and Excel.
The frequency polygon allows you to compare data with the naked eye.What is a frequency polygon?
A frequency polygon is a graphical tool that is used from a frequency histogram (that is, another type of graph that expresses frequencies using vertical columns). To do this, the different midpoints of the histogram columns are joined with a line, without leaving space between one and the other, thus achieving a geometric form or polygon.
With this graphic tool can be represented variables quantitative or different distributions, which is traditionally not done by a histogram, in a quick and easy way. It also has the virtue to be visible to the naked eye.
For this reason it is highly used within the social Sciences Y economic Sciences, thus allowing to establish comparisons useful between the different results of the same process.
Characteristics of the frequency polygon
Frequency polygons are formed by joining the midpoints of each phase or column by line segments, so that they consist of a type of visual representation of quantitative information. The data in the table is always below the curvature of the polygon, and its highest point is always the one with the highest frequency in the set.
What is a frequency polygon for?
Frequency polygons are used when it is necessary to graph or highlight different joint distributions or a cross-classification of a continuous quantitative variable, together with another discrete qualitative or quantitative variable, all within the same graph.
How to make a frequency polygon?
The frequency polygon arises from a histogram.As we have already said, a frequency polygon is always obtained from a frequency histogram, when all the midpoints of each element with their respective frequency are consequently joined. To do this, the following steps must be followed:
- Collect quantitative information on what will be studied. Then the lower and upper limits of all the elements studied will be established.
- Determine the frequency of each type of element within the limits established, and the average calculation of the limits will be made.
- Draw the closed line graph, joining the midpoints of the data obtained.
Examples of frequency polygons
Frequency polygon in Excel
Excel allows you to graphically represent the loaded data.To make a frequency polygon using the computer tool of Microsoft Excel, we must follow the following steps:
- First obtain the data table from which you want to graph a frequency polygon.
- Find the menu "insert", and choose the options "graphic", then "line" and finally "line with markers".
- A blank box will appear.
- In the box, in the range of the graph, place the data from the frequency column.
- In the same box, on the horizontal axis, choose the "edit" option to place the mean.
- Press "accept" to obtain the graph. Remember that it must be a closed chart, so often we will have to add data for the new intervals (in that case we will add the number 0 to each one).