Frequency Distributions
In statistics, a lot of tests are run using many different points of data and it’s important to understand how those data are spread out and what their individual values are in comparison with other data points. A frequency distribution is just that – an outline of what the data look like as a unit. A frequency table is one way to go about this. It’s an organized tabulation showing the number of individuals located in each category on the scale of measurement. When used in a table, you are given each score from highest to lowest (X) and next to it the number of times that score appears in the data (f). A table in which one is able to read the scores that appear in a data set and how often those particular scores appear in the data set. Here’s a link to a Khan Academy video we found to be helpful in explaining this concept.
Organizing Data into a Frequency Distribution
- Find the range
- Order the table from highest score to lowest score, not skipping scores that might not have shown up in the data set.
- In the next column, document how many times this score shows up in the data set
Organizing data into a group frequency table
- The grouped frequency table should have about 10 intervals. A good strategy is to come up with some widths according to Guideline 2 and divide the total range of numbers by that width to see if there are close to 10 intervals.
- The width of the interval should be a relatively simple number (like 2, 5, or 10)
- The bottom score in each class interval should be a multiple of the width (0-9, 10-19, 20-19, etc.)
- All intervals should be the same width.