How to make a frequency chart and determine frequency
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 occurs.
Step 1: Make a chart for your data. For this example, let’s say you’ve been given a list of twenty blood types for incoming 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.