Chapter 9 - Data Handling

Introduction to Data Handling

Data can be anything; it may consist of numbers, names, figures, or things. Data is organized in the form of graphs, charts, or tables.

Data are facts and figures that we use to get certain conclusions. For example, if your favourite books are Narnia, Harry Potter, and the Jungle Book, then you are fantasy lover!

Data is Vital

The Census of India is a large-scale survey of the country's population. The survey is done every 10 years.


From this data, we can find out the population of different states, which is vital information.

Data Collection

Data can be collected by observation, surveys, or by doing experiments.

  • Observation: To find out how long your plant takes to grow.
  • Survey: To find out how many of your friends like Chemistry.
  • Experiments: To find out how many people may get affected by a disease.

It is important to learn how to collect the right data and how to manage it.

Recording and Organising Data

Collection of data is also called recording of data. Once the data is recorded, the next job is to organize it efficiently.

A random organization of data may not be useful all the time but a well-organized data is pretty useful to derive useful conclusion.

Recording Data

Data should be recorded as per the requirement.

Example: A teacher collects the marks obtained by 6 students in a batch to analyze their performance in Algebra. He finds that Jenny scored 8 out of 20, Maino scored 11 out of 20, Nick scored 19 out of 20, Saira scored 16 out of 20, Mary scored 2 out of 20, and Charles scored 10 out of 20.

Student Marks
Jenny 8
Maino 11
Nick 19
Saira 16
Mary 2
Charles 10

From this data, Nick is good at algebra while Mary is poor.

Organizing Data

Data has to be first organized properly in order to derive correct conclusions. Data can be organised in the following ways:

Organizing Data

Tally Marks

Tally mark is a way to represent data. In this method, it is usual to express numbers with the help of vertical lines. The numbers are usually represented as groups of 5. Tally marks representation of some numbers are given here:

Number Tally mark representation
3 |||
5 ||||
8 |||| |||

Example: Suppose 15 of your friends like different flavors of ice-cream. You organize the data in the following manner:

Vanilla, Butter pecan, Vanilla, Strawberry, chocolate, Butter Pecan, Chocolate, Butter Pecan, Strawberry, Chocolate, Chocolate, Vanilla, Butter Pecan, Chocolate, Strawberry

The tally mark representation will be:

Flavor of ice-cream Number of friends like Tally mark representation
Vanilla 3 |||
Butter Pecan 4 ||||
Strawberry 3 |||
Chocolate 5 ||||



Petroglyphs are images carved on rock surface. It is an art of writing that the ancient men used to express themselves.



Pictograph is a form of representing data with the help of pictures. One can easily analyze data if it is represented as pictures.


From the above pictograph, one can easily conclude that the yellow flowers are the least and the blue flowers are the most.

Assume we have 500 red flowers and 100 purple flowers. In such cases, we can use one picture to represent 100 flowers.

How to Represent Fractions

Observe the following pictograph. Here, 1 picture represents 10 cupcakes.


We have 15 salted caramel cupcake, which is represented as one-and-a-half pictures.

Bar Graphs

Pictograph and tally charts have limitations.

  • Tally charts are not an efficient method to represent very large data.
  • In pictographs, it is not always easy to divide a picture to represent fractions.

A bar graph is a way to represent data that overcomes these problems.

Bar Graph

A bar graph consists of several bars of uniform width. These bars are drawn horizontally or vertically with equal spacing between them. The length of each bar represents a specific number.

Example: There are 15 students in a class. 3 students out of them like vanilla ice-cream, 3 like strawberry, 4 like butter pecan, and the remaining 5 like chocolate. Let us plot this data in a bar graph.

  • Draw two line: one horizontal and one vertical.
  • On the horizontal line, write down the flavors of ice-cream.
  • On the vertical line, mark the numbers using a scale.
  • Now, draw bars of uniform width to show how many students like which flavor.

The bar graph will look like:

Bar Graph

Bars can also be plotted horizontally. For example,


We use different scales to represent different data. When data is small, we use one unit to represent one object. When data is large, we can use one unit to represent many number of objects.

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