NCERT Textbook: Understanding Data | Informatics Practices for Class 11 - Humanities/Arts PDF Download

 Page 1


5.1 Introduct Ion to d ata Many a time, people take decisions based on 
certain data or information. For example, while 
choosing a college for getting admission, one 
looks at placement data of previous years of that 
college, educational qualification and experience 
of the faculty members, laboratory and hostel 
facilities, fees, etc. So we can say that identification 
of a college is based on various data and their 
analysis. Governments systematically collect 
and record data about the population through 
a process called census. Census data contains 
“Data is not information, Information 
is not knowledge, Knowledge is not 
understanding, Understanding is not 
wisdom.” 
— Gary Schubert 
In this chapter
 » Introduction to Data 
 » Data Collection
 » Data Storage
 » Data Processing 
 » Statistical Techniques 
for Data Processing
Understanding 
Data
Chapter 
5 
Chap 5.indd   81 09-Aug-19   11:49:18 AM
2024-25
Page 2


5.1 Introduct Ion to d ata Many a time, people take decisions based on 
certain data or information. For example, while 
choosing a college for getting admission, one 
looks at placement data of previous years of that 
college, educational qualification and experience 
of the faculty members, laboratory and hostel 
facilities, fees, etc. So we can say that identification 
of a college is based on various data and their 
analysis. Governments systematically collect 
and record data about the population through 
a process called census. Census data contains 
“Data is not information, Information 
is not knowledge, Knowledge is not 
understanding, Understanding is not 
wisdom.” 
— Gary Schubert 
In this chapter
 » Introduction to Data 
 » Data Collection
 » Data Storage
 » Data Processing 
 » Statistical Techniques 
for Data Processing
Understanding 
Data
Chapter 
5 
Chap 5.indd   81 09-Aug-19   11:49:18 AM
2024-25
82
Informat Ics Pract Ices – c lass XI
valuable information which are helpful is planning and 
formulating policies. Likewise, the coaching staff of a 
sports team analyses previous performances of opponent 
teams for making strategies. Banks maintain data about 
the customers, their account details and transactions. 
All these examples highlight the need of data in various 
fields. Data are indeed crucial for decision making. 
In the previous examples, one cannot make decisions 
by looking at the data itself. In our example of choosing 
a college, suppose the placement cell of the college has 
maintained data of about 2000 students placed with 
different companies at different salary packages in the 
last 3 years. Looking at such data, one cannot make 
any remark about the placement of students of that 
college. The college processes and analyses this data 
and the results are given in the placement brochure of 
the college through summarisation as well as visuals for 
easy understanding. Hence, data need to be gathered, 
processed and analysed for making decisions. 
In general, data is a collection of characters, numbers, 
and other symbols that represents values of some 
situations or variables. Data is plural and singular of the 
word data is “datum”. Using computers, data are stored 
in electronic forms because data processing becomes 
faster and easier as compared to manual data processing 
done by people. The Information and Communication 
Technology (ICT) revolution led by computer, mobile and 
Internet has resulted in generation of large volume of 
data and at a very fast pace. The following list contains 
some examples of data that we often come across.
• Name, age, gender, contact details, etc., of a person
• Transactions data generated through banking, 
ticketing, shopping, etc. whether online or offline
• Images, graphics, animations, audio, video
• Documents and web pages
• Online posts, comments and messages 
• Signals generated by sensors
• Satellite data including meteorological data, 
communication data, earth observation data, etc.
5.1.1 Importance of Data
Human beings rely on data for making decisions. 
Besides, large amount of data when processed with the 
help of a computer, show us the possibilities or hidden 
A knowledge base is 
a store of information 
consisting of facts, 
assumptions and 
rules which an AI 
system can use for 
decision making.
Chap 5.indd   82 09-Aug-19   11:49:19 AM
2024-25
Page 3


5.1 Introduct Ion to d ata Many a time, people take decisions based on 
certain data or information. For example, while 
choosing a college for getting admission, one 
looks at placement data of previous years of that 
college, educational qualification and experience 
of the faculty members, laboratory and hostel 
facilities, fees, etc. So we can say that identification 
of a college is based on various data and their 
analysis. Governments systematically collect 
and record data about the population through 
a process called census. Census data contains 
“Data is not information, Information 
is not knowledge, Knowledge is not 
understanding, Understanding is not 
wisdom.” 
— Gary Schubert 
In this chapter
 » Introduction to Data 
 » Data Collection
 » Data Storage
 » Data Processing 
 » Statistical Techniques 
for Data Processing
Understanding 
Data
Chapter 
5 
Chap 5.indd   81 09-Aug-19   11:49:18 AM
2024-25
82
Informat Ics Pract Ices – c lass XI
valuable information which are helpful is planning and 
formulating policies. Likewise, the coaching staff of a 
sports team analyses previous performances of opponent 
teams for making strategies. Banks maintain data about 
the customers, their account details and transactions. 
All these examples highlight the need of data in various 
fields. Data are indeed crucial for decision making. 
In the previous examples, one cannot make decisions 
by looking at the data itself. In our example of choosing 
a college, suppose the placement cell of the college has 
maintained data of about 2000 students placed with 
different companies at different salary packages in the 
last 3 years. Looking at such data, one cannot make 
any remark about the placement of students of that 
college. The college processes and analyses this data 
and the results are given in the placement brochure of 
the college through summarisation as well as visuals for 
easy understanding. Hence, data need to be gathered, 
processed and analysed for making decisions. 
In general, data is a collection of characters, numbers, 
and other symbols that represents values of some 
situations or variables. Data is plural and singular of the 
word data is “datum”. Using computers, data are stored 
in electronic forms because data processing becomes 
faster and easier as compared to manual data processing 
done by people. The Information and Communication 
Technology (ICT) revolution led by computer, mobile and 
Internet has resulted in generation of large volume of 
data and at a very fast pace. The following list contains 
some examples of data that we often come across.
• Name, age, gender, contact details, etc., of a person
• Transactions data generated through banking, 
ticketing, shopping, etc. whether online or offline
• Images, graphics, animations, audio, video
• Documents and web pages
• Online posts, comments and messages 
• Signals generated by sensors
• Satellite data including meteorological data, 
communication data, earth observation data, etc.
5.1.1 Importance of Data
Human beings rely on data for making decisions. 
Besides, large amount of data when processed with the 
help of a computer, show us the possibilities or hidden 
A knowledge base is 
a store of information 
consisting of facts, 
assumptions and 
rules which an AI 
system can use for 
decision making.
Chap 5.indd   82 09-Aug-19   11:49:19 AM
2024-25
Understanding d ata 83
traits which are otherwise not visible to humans. When 
one withdraws money from ATM, the bank needs to debit 
the withdrawn amount from the linked account. So the 
bank needs to maintain data and update it as and when 
required. The meteorological offices continuously keep 
on monitoring satellite data for any upcoming cyclone 
or heavy rain. 
In a competitive business environment, it is important 
for business organisations to continuously monitor and 
analyse market behavior with respect to their products 
and take actions accordingly. Besides, companies 
identify customer demands as well as feedbacks, and 
make changes in their products or services accordingly. 
The dynamic pricing concept used by airlines and 
railway is another example where they decide the price 
based on relationships between demand and supply. 
The cab booking Apps increase or decrease the price 
based on demand for cabs at a particular time. Certain 
restaurants offer discounted price (called happy hours), 
they decide when and how much discount to offer by 
analysing sales data at different time periods. 
Besides business, following are some other scenarios 
where data are also stored and analysed for making 
decisions: 
• The electronic voting machines are used for recording 
the votes cast. Subsequently, the voting data from 
all the machines are accumulated to declare election 
results in a short time as compared to manual 
counting of ballot papers. 
• Scientists record data while doing experiments to 
calculate and compare results. 
• Pharmaceutical companies record data while trying 
out a new medicine to see its effectiveness. 
• Libraries maintain data about books in the library 
and the membership of the library.
• The search engines give us results after analysing 
large volume of data available on the websites across 
World Wide Web (www).
• Weather alerts are generated by analysing data 
received from various satellites.
5.1.2 Types of Data
As data come from different sources, they can be in 
different formats. For example, an image is a collection 
n otes Chap 5.indd   83 09-Aug-19   11:49:19 AM
2024-25
Page 4


5.1 Introduct Ion to d ata Many a time, people take decisions based on 
certain data or information. For example, while 
choosing a college for getting admission, one 
looks at placement data of previous years of that 
college, educational qualification and experience 
of the faculty members, laboratory and hostel 
facilities, fees, etc. So we can say that identification 
of a college is based on various data and their 
analysis. Governments systematically collect 
and record data about the population through 
a process called census. Census data contains 
“Data is not information, Information 
is not knowledge, Knowledge is not 
understanding, Understanding is not 
wisdom.” 
— Gary Schubert 
In this chapter
 » Introduction to Data 
 » Data Collection
 » Data Storage
 » Data Processing 
 » Statistical Techniques 
for Data Processing
Understanding 
Data
Chapter 
5 
Chap 5.indd   81 09-Aug-19   11:49:18 AM
2024-25
82
Informat Ics Pract Ices – c lass XI
valuable information which are helpful is planning and 
formulating policies. Likewise, the coaching staff of a 
sports team analyses previous performances of opponent 
teams for making strategies. Banks maintain data about 
the customers, their account details and transactions. 
All these examples highlight the need of data in various 
fields. Data are indeed crucial for decision making. 
In the previous examples, one cannot make decisions 
by looking at the data itself. In our example of choosing 
a college, suppose the placement cell of the college has 
maintained data of about 2000 students placed with 
different companies at different salary packages in the 
last 3 years. Looking at such data, one cannot make 
any remark about the placement of students of that 
college. The college processes and analyses this data 
and the results are given in the placement brochure of 
the college through summarisation as well as visuals for 
easy understanding. Hence, data need to be gathered, 
processed and analysed for making decisions. 
In general, data is a collection of characters, numbers, 
and other symbols that represents values of some 
situations or variables. Data is plural and singular of the 
word data is “datum”. Using computers, data are stored 
in electronic forms because data processing becomes 
faster and easier as compared to manual data processing 
done by people. The Information and Communication 
Technology (ICT) revolution led by computer, mobile and 
Internet has resulted in generation of large volume of 
data and at a very fast pace. The following list contains 
some examples of data that we often come across.
• Name, age, gender, contact details, etc., of a person
• Transactions data generated through banking, 
ticketing, shopping, etc. whether online or offline
• Images, graphics, animations, audio, video
• Documents and web pages
• Online posts, comments and messages 
• Signals generated by sensors
• Satellite data including meteorological data, 
communication data, earth observation data, etc.
5.1.1 Importance of Data
Human beings rely on data for making decisions. 
Besides, large amount of data when processed with the 
help of a computer, show us the possibilities or hidden 
A knowledge base is 
a store of information 
consisting of facts, 
assumptions and 
rules which an AI 
system can use for 
decision making.
Chap 5.indd   82 09-Aug-19   11:49:19 AM
2024-25
Understanding d ata 83
traits which are otherwise not visible to humans. When 
one withdraws money from ATM, the bank needs to debit 
the withdrawn amount from the linked account. So the 
bank needs to maintain data and update it as and when 
required. The meteorological offices continuously keep 
on monitoring satellite data for any upcoming cyclone 
or heavy rain. 
In a competitive business environment, it is important 
for business organisations to continuously monitor and 
analyse market behavior with respect to their products 
and take actions accordingly. Besides, companies 
identify customer demands as well as feedbacks, and 
make changes in their products or services accordingly. 
The dynamic pricing concept used by airlines and 
railway is another example where they decide the price 
based on relationships between demand and supply. 
The cab booking Apps increase or decrease the price 
based on demand for cabs at a particular time. Certain 
restaurants offer discounted price (called happy hours), 
they decide when and how much discount to offer by 
analysing sales data at different time periods. 
Besides business, following are some other scenarios 
where data are also stored and analysed for making 
decisions: 
• The electronic voting machines are used for recording 
the votes cast. Subsequently, the voting data from 
all the machines are accumulated to declare election 
results in a short time as compared to manual 
counting of ballot papers. 
• Scientists record data while doing experiments to 
calculate and compare results. 
• Pharmaceutical companies record data while trying 
out a new medicine to see its effectiveness. 
• Libraries maintain data about books in the library 
and the membership of the library.
• The search engines give us results after analysing 
large volume of data available on the websites across 
World Wide Web (www).
• Weather alerts are generated by analysing data 
received from various satellites.
5.1.2 Types of Data
As data come from different sources, they can be in 
different formats. For example, an image is a collection 
n otes Chap 5.indd   83 09-Aug-19   11:49:19 AM
2024-25
84
Informat Ics Pract Ices – c lass XI
of pixels; a video is made up of frames; a fee slip is 
made up of few numeric and non-numeric entries; and 
messages/chats are made up of texts, icons (emoticons) 
and images/videos. Two broad categories in which data 
can be classified on the basis of their format are:
(A) Structured Data
Data which is organised and can be recorded in a well 
defined format is called structured data. Structured 
data is usually stored in computer in a tabular (in rows 
and columns) format where each column represents 
different data for a particular parameter called attribute/
characteristic/variable and each row represents data of 
an observation for different attributes. Table 5.1 shows 
structured data related to an inventory of kitchen items 
maintained by a shop. 
Given this data, using a spreadsheet or other such 
software, the shop owner can find out how many total 
items are there by summing the column Items_in_
Inventory of Table 5.1 The owner of the shop can also 
calculate the total value of all items in the inventory 
by multiplying each entry of column 3 (Unit Price) with 
corresponding entry of column 5 (Items_in_Inventory) 
and finding their sum. 
Table 5.2 shows more examples of structured data 
recorded for different attributes. 
Table 5.2 Attributes maintained for different activities
Entity/Activities Data Fields/Parameters/Attributes
Books at a shop BookTitle, Author, Price, YearofPublication 
Depositing fees in a school StudentName, Class, RollNo, FeesAmount, DepositDate
Amount withdrawal from ATM AccHolderName, AccountNo, TypeofAcc, DateofWithdrawal, 
AmountWithdrawn, ATMid, TimeOfWithdrawal
Table 5.1 Structured data about kitchen items in a shop
ModelNo ProductName Unit Price Discount(%) Items_in_Inventory
ABC1 Water bottle 126 8 13
ABC2 Melamine Plates 320 5 45
ABC3 Dinner Set 4200 10 8
GH67 Jug 80 0 10
GH78 Table Spoon 120 5 14
GH81 Bucket 190 12 6
NK2 Kitchen Towel 25 0 32
Activity 5.1
Observe Voter Identity 
cards of your family 
members and identify 
the data fields under 
which data are 
organised. Are they 
same for all? 
Chap 5.indd   84 09-Aug-19   11:49:19 AM
2024-25
Page 5


5.1 Introduct Ion to d ata Many a time, people take decisions based on 
certain data or information. For example, while 
choosing a college for getting admission, one 
looks at placement data of previous years of that 
college, educational qualification and experience 
of the faculty members, laboratory and hostel 
facilities, fees, etc. So we can say that identification 
of a college is based on various data and their 
analysis. Governments systematically collect 
and record data about the population through 
a process called census. Census data contains 
“Data is not information, Information 
is not knowledge, Knowledge is not 
understanding, Understanding is not 
wisdom.” 
— Gary Schubert 
In this chapter
 » Introduction to Data 
 » Data Collection
 » Data Storage
 » Data Processing 
 » Statistical Techniques 
for Data Processing
Understanding 
Data
Chapter 
5 
Chap 5.indd   81 09-Aug-19   11:49:18 AM
2024-25
82
Informat Ics Pract Ices – c lass XI
valuable information which are helpful is planning and 
formulating policies. Likewise, the coaching staff of a 
sports team analyses previous performances of opponent 
teams for making strategies. Banks maintain data about 
the customers, their account details and transactions. 
All these examples highlight the need of data in various 
fields. Data are indeed crucial for decision making. 
In the previous examples, one cannot make decisions 
by looking at the data itself. In our example of choosing 
a college, suppose the placement cell of the college has 
maintained data of about 2000 students placed with 
different companies at different salary packages in the 
last 3 years. Looking at such data, one cannot make 
any remark about the placement of students of that 
college. The college processes and analyses this data 
and the results are given in the placement brochure of 
the college through summarisation as well as visuals for 
easy understanding. Hence, data need to be gathered, 
processed and analysed for making decisions. 
In general, data is a collection of characters, numbers, 
and other symbols that represents values of some 
situations or variables. Data is plural and singular of the 
word data is “datum”. Using computers, data are stored 
in electronic forms because data processing becomes 
faster and easier as compared to manual data processing 
done by people. The Information and Communication 
Technology (ICT) revolution led by computer, mobile and 
Internet has resulted in generation of large volume of 
data and at a very fast pace. The following list contains 
some examples of data that we often come across.
• Name, age, gender, contact details, etc., of a person
• Transactions data generated through banking, 
ticketing, shopping, etc. whether online or offline
• Images, graphics, animations, audio, video
• Documents and web pages
• Online posts, comments and messages 
• Signals generated by sensors
• Satellite data including meteorological data, 
communication data, earth observation data, etc.
5.1.1 Importance of Data
Human beings rely on data for making decisions. 
Besides, large amount of data when processed with the 
help of a computer, show us the possibilities or hidden 
A knowledge base is 
a store of information 
consisting of facts, 
assumptions and 
rules which an AI 
system can use for 
decision making.
Chap 5.indd   82 09-Aug-19   11:49:19 AM
2024-25
Understanding d ata 83
traits which are otherwise not visible to humans. When 
one withdraws money from ATM, the bank needs to debit 
the withdrawn amount from the linked account. So the 
bank needs to maintain data and update it as and when 
required. The meteorological offices continuously keep 
on monitoring satellite data for any upcoming cyclone 
or heavy rain. 
In a competitive business environment, it is important 
for business organisations to continuously monitor and 
analyse market behavior with respect to their products 
and take actions accordingly. Besides, companies 
identify customer demands as well as feedbacks, and 
make changes in their products or services accordingly. 
The dynamic pricing concept used by airlines and 
railway is another example where they decide the price 
based on relationships between demand and supply. 
The cab booking Apps increase or decrease the price 
based on demand for cabs at a particular time. Certain 
restaurants offer discounted price (called happy hours), 
they decide when and how much discount to offer by 
analysing sales data at different time periods. 
Besides business, following are some other scenarios 
where data are also stored and analysed for making 
decisions: 
• The electronic voting machines are used for recording 
the votes cast. Subsequently, the voting data from 
all the machines are accumulated to declare election 
results in a short time as compared to manual 
counting of ballot papers. 
• Scientists record data while doing experiments to 
calculate and compare results. 
• Pharmaceutical companies record data while trying 
out a new medicine to see its effectiveness. 
• Libraries maintain data about books in the library 
and the membership of the library.
• The search engines give us results after analysing 
large volume of data available on the websites across 
World Wide Web (www).
• Weather alerts are generated by analysing data 
received from various satellites.
5.1.2 Types of Data
As data come from different sources, they can be in 
different formats. For example, an image is a collection 
n otes Chap 5.indd   83 09-Aug-19   11:49:19 AM
2024-25
84
Informat Ics Pract Ices – c lass XI
of pixels; a video is made up of frames; a fee slip is 
made up of few numeric and non-numeric entries; and 
messages/chats are made up of texts, icons (emoticons) 
and images/videos. Two broad categories in which data 
can be classified on the basis of their format are:
(A) Structured Data
Data which is organised and can be recorded in a well 
defined format is called structured data. Structured 
data is usually stored in computer in a tabular (in rows 
and columns) format where each column represents 
different data for a particular parameter called attribute/
characteristic/variable and each row represents data of 
an observation for different attributes. Table 5.1 shows 
structured data related to an inventory of kitchen items 
maintained by a shop. 
Given this data, using a spreadsheet or other such 
software, the shop owner can find out how many total 
items are there by summing the column Items_in_
Inventory of Table 5.1 The owner of the shop can also 
calculate the total value of all items in the inventory 
by multiplying each entry of column 3 (Unit Price) with 
corresponding entry of column 5 (Items_in_Inventory) 
and finding their sum. 
Table 5.2 shows more examples of structured data 
recorded for different attributes. 
Table 5.2 Attributes maintained for different activities
Entity/Activities Data Fields/Parameters/Attributes
Books at a shop BookTitle, Author, Price, YearofPublication 
Depositing fees in a school StudentName, Class, RollNo, FeesAmount, DepositDate
Amount withdrawal from ATM AccHolderName, AccountNo, TypeofAcc, DateofWithdrawal, 
AmountWithdrawn, ATMid, TimeOfWithdrawal
Table 5.1 Structured data about kitchen items in a shop
ModelNo ProductName Unit Price Discount(%) Items_in_Inventory
ABC1 Water bottle 126 8 13
ABC2 Melamine Plates 320 5 45
ABC3 Dinner Set 4200 10 8
GH67 Jug 80 0 10
GH78 Table Spoon 120 5 14
GH81 Bucket 190 12 6
NK2 Kitchen Towel 25 0 32
Activity 5.1
Observe Voter Identity 
cards of your family 
members and identify 
the data fields under 
which data are 
organised. Are they 
same for all? 
Chap 5.indd   84 09-Aug-19   11:49:19 AM
2024-25
Understanding d ata 85
(B) Unstructured Data
A newspaper contains various types of news items 
which are also called data. But there is no fixed pattern 
that a newspaper follows in placing news articles. One 
day there might be three images of different sizes on 
a page along with five news items and one or more 
advertisements. While on another day there, might be 
one big image with three textual news items. So there is 
no particular format nor any fixed structure for printing 
news. Another example is the content of an email. 
There is no fixed structure about how many lines or 
paragraphs one has to write in an email or how many 
files are to be attached with an email. In summary, 
data which are not in the traditional row and column 
structure is called unstructured data. 
Examples of unstructured data include web pages 
consisting of text as well as multimedia contents 
(image, graphics, audio/video). Other examples include 
text documents, business reports, books, audio/video 
files, social media messages. Although there are ways 
to process unstructured data, we are going to focus on 
handling structured data only in this book.
Unstructured data are sometimes described with 
the help of some other data called metadata. Metadata 
is basically data about data. For example, we describe 
different parts of an email as subject, recipient, main 
body, attachment, etc. These are the metadata for the 
email data. Likewise, we can have some metadata for an 
image file as image size (in KB or MB), image type (for 
example, JPEG, PNG), image resolution, etc.
5.2 d ata c ollect Ion For processing data, we need to collect or gather data 
first. We can then store the data in a file or database 
for later use. Data collection here means identifying 
already available data or collecting from the appropriate 
sources. Suppose there are three different scenarios 
where sales data in a grocery store are available:
• Sales data are available with the shopkeeper in a 
diary or register. In this case we should enter the 
data in a digital format for example, in a spreadsheet.
• Data are already available in a digital format, say in 
a CSV (comma separated values) file.
• The shopkeeper has so far not recorded any data in 
either form but wants to get a software developed for 
Think and Reflect
When we click a 
photograph using 
our digital or mobile 
camera, does it have 
some metadata 
associated with it?
Chap 5.indd   85 09-Aug-19   11:49:19 AM
2024-25