Descriptive Statistics > Make a Frequency Chart
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 ten students score 80 in statistics, then the score of 80 has a frequency of 10. 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: Make 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.
On the horizontal axis, write “frequency (#)” and “percent (%)”. On the vertical axis, write your list of items. 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.
Use the formula % = (f / n) × 100 to fill in the next column. In this example, n = total amount of items in your data = 20. A appears
5 times (frequency in this formula is just the number of times the item appears). 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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