Frequency distribution I

In this page 'Frequency distribution I' we are going to discuss about frequency distribution. Frequency distribution is the arrangement of raw data into tabular form. The data can be arranged into classes according to the size along with the corresponding frequencies.

Frequency is how often something occurs

For example Peter played soccer on

  • Sunday morning
  • Sunday evening
  • Wednesday morning
  • Friday evening

Here the frequency is 2 on Sunday and 1 on Wednesday and 1 on Friday. The total number of times is 4 and it is for the whole week.

This distributions summarize and compress data by grouping into classes and recording how many data falls into each class.

The arrangement of collected data are classified as

  • Ungrouped data
  • Grouped data
  • Array.

Ungrouped data or raw data: Data which has not been arranged in systematic order is called ungrouped data

Grouped data: Data that has been organized into groups is known as classes. Each of these classes is of certain width which is known as class interval or class size. All classes may have same size or different class size depending on how we are grouping data. The class interval is always a whole number.

Array: The numerical raw data that is arranged in ascending or descending order is called array.

Advantage and disadvantage of this topic:


  • Condense and summarize large amount of data into useful format
  • Permits cautious comparison of data set.
  • Describe all variable types.
  • Makes list more intelligible.

 To understand this topic more clearly let us look a example

Suppose there are 17 students in a section of class IX and the marks scored by them in a test are as follows.


First let us arrange them in the ascending order.


Now we can use classes like 1-3,4-6,7-9 which means that the variables values are grouped together.

       While marking the tally, the fifth entry is denoted by \ line.  So //\// denotes the frequency 5.


Tally marks


1- 3








This is the frequency table for grouped data.This table shows that number of students who had scored marks in the particular interval of the given test. More problems are discussed in the following pages. If you are having any doubts you can contact us through mail, we will help you to clear all your doubts.

Basic statistics

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