A frequency distribution is a summary of how often each different value occurs in a dataset. It can be represented in a table or graphically, such as in histograms or pie charts.
There are several types of frequency distributions, each suited to different kinds of data and analytical needs.
Let's explore discrete, continuous, and cumulative frequency distributions, providing an example of each.
1. Discrete Frequency Distribution
Discrete frequency distribution is used for categorical or countable data where the values are distinct and separate.
This type is often used for data that can be counted in whole numbers.
Example: Consider a survey of 20 students asking how many books they read in the past month, resulting in the following data: 0, 1, 2, 1, 3, 2, 0, 1, 4, 2, 0, 1, 3, 2, 0, 1, 4, 2, 0, 1.
This table shows the discrete frequency distribution of the number of books read by students.
2. Continuous Frequency Distribution
Continuous frequency distribution is used for data that can take any value within a range.
Values are grouped into intervals since the data can be infinitely divisible.
Example: Suppose we measure the heights (in cm) of a group of 20 people and get the following intervals:
This table represents a continuous frequency distribution, where the heights are grouped into intervals since individual measurements can vary widely.
3. Cumulative Frequency Distribution
Cumulative frequency distribution shows the sum of frequencies accumulated up to a certain point in the dataset. It can be applied to both discrete and continuous data.
Example (based on the discrete data from above):
The "Cumulative Frequency" column shows the running total of books read. For instance, 11 students have read up to 1 book, 16 students have read up to 2 books, and so on, until all 20 students are accounted for.
Each type of frequency distribution serves a different purpose and helps in the analysis of various kinds of data, whether it's countable, measurable on a continuous scale, or if you're interested in the accumulation of frequencies up to certain values.