## Make a Frequency Chart: Overview

If you are asked to determine a frequency in statistics, it doesn’t just mean that you should just count out the number of times something happens. It usually involves you having to make a frequency chart to display a list of frequencies.

- A
**frequency**is the number of times a data value occurs. For example, if four people have an IQ of between 118 and 125, then an IQ of 118 to 125 has a frequency of 4. Frequency is often represented by the letter**f.** - A
**frequency chart**is made by arranging data values in ascending order of magnitude along with their frequencies.

## Make a Frequency Chart: Steps

Step 1: **Draw a chart for your data**. For this example, you’ve been given a list of twenty blood types for emergency surgery patients:

- A, O, A, B, B, AB, B, B, O, A, O, O, O, AB, B, AB, AB, A, O, A.

Write “frequency (#)” and “percent (%)” on the top row. Write your list of items in the first column. In this example, we have four distinct blood types: A, B, AB, and O.

Step 2: **Count the number of times each item appears** in your data.

In this example, we have:

- A appears 5 times.
- B appears 5 times.
- O appears 6 times.
- AB appears 4 times.

Write those in the “number” column (#). This is your **frequency.**

Step 3:**Use the formula % = (f / n) × 100 to fill in the next column.** In this example:

- n = total amount of items in your data = 20.
- f = frequency (the number of times the item appears).

“A” appears

5 times . So we have:

(5 / 20) × 100 = 25%

Fill in the rest of the frequency column, changing the ‘f’ for each blood type.

That’s it!

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## References

Beyer, W. H. CRC Standard Mathematical Tables, 31st ed. Boca Raton, FL: CRC Press, pp. 536 and 571, 2002.

Agresti A. (1990) Categorical Data Analysis. John Wiley and Sons, New York.

Everitt, B. S.; Skrondal, A. (2010), The Cambridge Dictionary of Statistics, Cambridge University Press.

Lindstrom, D. (2010). Schaum’s Easy Outline of Statistics, Second Edition (Schaum’s Easy Outlines) 2nd Edition. McGraw-Hill Education