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).
5 times . So we have:
(5 / 20) × 100 = 25%
Fill in the rest of the frequency column, changing the ‘f’ for each blood type.
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Beyer, W. H. CRC Standard Mathematical Tables, 31st ed. Boca Raton, FL: CRC Press, pp. 536 and 571, 2002.
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Lindstrom, D. (2010). Schaum’s Easy Outline of Statistics, Second Edition (Schaum’s Easy Outlines) 2nd Edition. McGraw-Hill Education
Stephanie Glen. "Make a Frequency Chart and Determine Frequency" From StatisticsHowTo.com: Elementary Statistics for the rest of us! https://www.statisticshowto.com/probability-and-statistics/descriptive-statistics/how-to-make-a-frequency-chart-and-determine-frequency/
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