Frequency Tables and Distributions
When working with raw data, the first challenge is understanding what the data actually looks like. Large lists of numbers are difficult to interpret directly.
Frequency tables help us organize data so patterns, counts, and distributions become clear and easy to understand.
What Is a Frequency Table?
A frequency table is a structured way of showing how often each value (or group of values) appears in a dataset.
Instead of looking at raw data, frequency tables summarize the data by counting occurrences.
Simple Real-World Example
Suppose a teacher records the marks of 10 students:
60, 70, 70, 75, 80, 80, 80, 85, 90, 90
Looking at this list directly is not very informative. A frequency table shows how many times each score occurs.
From this, we can easily see which scores are common and which are rare.
Why Frequency Tables Are Important
- They organize raw data
- They make patterns visible
- They help identify most common values
- They are the foundation for graphs and charts
Most statistical analysis begins with organizing data into frequency tables.
Frequency Distribution
A frequency distribution shows how data is distributed across different values or ranges.
Instead of listing individual observations, data is grouped to understand its overall behavior.
Frequency distributions are commonly used for:
- Exam scores
- Customer ages
- Product prices
- Survey responses
Grouped Frequency Distribution (Concept)
When datasets are large, values are grouped into intervals called class intervals.
For example, instead of listing every age, we may group ages as:
- 10–19
- 20–29
- 30–39
This makes large datasets easier to analyze and visualize.
Numerical Example (Step-by-Step)
A store records the number of customers per day over 7 days:
45, 50, 52, 50, 48, 45, 50
By counting occurrences:
- 45 appears 2 times
- 50 appears 3 times
- 48 appears 1 time
- 52 appears 1 time
This gives a clear picture of daily customer flow.
Practice Quiz
Question 1:
Why are frequency tables useful?
Question 2:
Which situation is best suited for a frequency distribution?
- A. Listing names of employees
- B. Recording daily temperatures
- C. Writing a company description
Question 3:
What is the main advantage of grouped frequency distributions?
Mini Practice (Think & Apply)
A gym records the ages of its members.
- Would a frequency table help?
- Would grouping ages into ranges be better?
What’s Next
In the next lesson, we will study Mean, Median, and Mode, which are key measures used to describe the center of a dataset.