Important terminology:
How to make a frequency distribution: 1. Decide how many classes you want to have 2. Find the class width and round the number (most of the time you round this number up) 3. Find the lowest data value in the data set, this will be the lowest class limit 4. Add the class with to the lowest class limit (from step 3). This is the second class’ lower limit. 5. Repeat step 4 until you exceed the highest value in the data set. 6. Find the upper class limits, add one minus the class width to each lower limit 7. Fill out the class section of the frequency distribution (the table below). 8. Find the class frequencies (number of values that fall within each class).
Relative frequency distributions: 9. Divide each class frequency by the sum of all frequencies.
Cumulative frequency distributions: 9. Using the upper class limits, at each limit add all frequencies below the upper class limit EXAMPLE 1:
I recently asked several tutors what their GPAs were, and got the following GPAs: 3.4, 3.7, 3.0, 3.9, 3.4, 3.1, 3.5, 3.8, 3.0, 3.5, 3.4, 3.4, 3.9, 3.8, 3.9, 3.2, 3.2
If I want to show the info in a frequency distribution. I’d follow these steps: 1. Decide how many classes you want to have
I want to have 5 classes
2. Find the class width and round the number (most of the time you round this number up)
Class width: (3.93.0) / 5 = 0.18 ≈ 0.2
3. Find the lowest data value in the data set, this will be the lowest class limit
3.0 is the lowest class limit
4. Add the class width to the lowest class limit (from step 3). This is the second class’ lower limit.
3.0 + 0.2 = 3.2
5. Repeat step 4 until you exceed the highest value in the data set.
6. Find the upper class limits, typically one minus the class width to each lower limit.
7. Fill out the class section of the frequency distribution (the table below).
8. Find the class frequencies (number of values that fall within each class).
Relative frequency distributions, follow steps 18 above and: 9. Divide each class frequency by the sum of all frequencies.
Relative frequency distribution:
Cumulative frequency distributions, follow steps 18 above and:
9. Using the upper class limits, at each limit add all frequencies below the Upper Class Limit (see below)

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