NCERT Textbook - Collection of Data Notes | Study Economics Class 11 - Commerce

 Page 1


Collection of Data
1. INTRODUCTION
In the previous chapter, you have read
about what is economics. You also
studied about the role and importance
of statistics in economics. In this
Studying this chapter should
enable you to:
• understand the meaning and
purpose of data collection;
• distinguish between primary and
secondary sources;
• know the mode of collection of data;
• distinguish between Census and
Sample Surveys;
• be familiar with the techniques of
sampling;
• know about some important sources
of secondary data.
chapter, you will study the sources of
data and the mode of data collection.
The purpose of collection of data is to
show evidence for reaching a sound and
clear solution to a problem.
In economics, you often come
across a statement like this,
“After many fluctuations the output
of food grains rose to 132 million tonnes
in 1978-79 from 108 million tonnes in
1970-71, but fell to 108 million tonnes
in 1979-80. Production of food grains
then rose continuously to 252 million
tonnes in 2015-16 and touched 272
million tonnes in 2016–17.”
In this statement, you can observe
that the food grains production in
different years does not remain the
same. It varies from year to year and
CHAPTER
2
2020-21
Page 2


Collection of Data
1. INTRODUCTION
In the previous chapter, you have read
about what is economics. You also
studied about the role and importance
of statistics in economics. In this
Studying this chapter should
enable you to:
• understand the meaning and
purpose of data collection;
• distinguish between primary and
secondary sources;
• know the mode of collection of data;
• distinguish between Census and
Sample Surveys;
• be familiar with the techniques of
sampling;
• know about some important sources
of secondary data.
chapter, you will study the sources of
data and the mode of data collection.
The purpose of collection of data is to
show evidence for reaching a sound and
clear solution to a problem.
In economics, you often come
across a statement like this,
“After many fluctuations the output
of food grains rose to 132 million tonnes
in 1978-79 from 108 million tonnes in
1970-71, but fell to 108 million tonnes
in 1979-80. Production of food grains
then rose continuously to 252 million
tonnes in 2015-16 and touched 272
million tonnes in 2016–17.”
In this statement, you can observe
that the food grains production in
different years does not remain the
same. It varies from year to year and
CHAPTER
2
2020-21
10 STATISTICS FOR ECONOMICS
from crop to crop. As these values vary,
they are called variable. The variables
are generally represented by the letters
X, Y or Z. Each value of a variable is an
observation. For example, the food
grain production in  India varies
between 108 million tonnes in 1970–
71  to 272 million tonnes  in 2016-17
as shown  in the following table. The
years are represented by variable X and
the production of food grain in India
(in million tonnes) is represented by
variable Y.
TABLE 2.1
Production of Food Grain in India
(Million Tonnes)
     X Y
1970–71 108
1978–79 132
1990–91 176
1997–98 194
2001–02 212
2015-16 252
2016-17 272
Here, the values of these variables
X and Y are the ‘data’, from which we
can obtain information about the
production of food grains in India. To
know the fluctuations in food grains
production, we need the ‘data’ on the
production of food grains in India for
various years. ‘Data’ is a tool, which
helps in understanding problems by
providing information.
You must be wondering where do
‘data’ come from and how do we collect
these? In the following sections we will
discuss the types of data, method and
instruments of data collection and
sources of obtaining data.
2. WHAT ARE THE SOURCES OF DATA?
Statistical data can be obtained from
two sources. The researcher may
collect the data by conducting an
enquiry. Such  data are called Primary
Data, as they are based on first hand
information. Suppose, you want to
know about the popularity of a filmstar
among school students. For  this, you
will have to enquire from a large
number of school students, by asking
questions from them to collect the
desired information. The data you get,
is an example of primary data.
If the data have been collected and
processed (scrutinised and tabulated)
by some other agency, they are called
Secondary Data.  They can be obtained
either from published sources such as
government reports, documents,
newspapers, books written by
economists or from any other source,
for example, a website. Thus, the data
are primary to the source that collects
and processes them for the first time
and secondary for all sources that later
use such data. Use of secondary data
saves time and cost. For example, after
collecting the data on the popularity of
the filmstar among students, you
publish a report. If somebody uses the
data collected by you for a similar
study, it becomes secondary data.
3. HOW DO WE COLLECT THE DATA?
Do you know how a manufacturer
decides about a product or how a
political party decides about a
candidate? They conduct a survey by
2020-21
Page 3


Collection of Data
1. INTRODUCTION
In the previous chapter, you have read
about what is economics. You also
studied about the role and importance
of statistics in economics. In this
Studying this chapter should
enable you to:
• understand the meaning and
purpose of data collection;
• distinguish between primary and
secondary sources;
• know the mode of collection of data;
• distinguish between Census and
Sample Surveys;
• be familiar with the techniques of
sampling;
• know about some important sources
of secondary data.
chapter, you will study the sources of
data and the mode of data collection.
The purpose of collection of data is to
show evidence for reaching a sound and
clear solution to a problem.
In economics, you often come
across a statement like this,
“After many fluctuations the output
of food grains rose to 132 million tonnes
in 1978-79 from 108 million tonnes in
1970-71, but fell to 108 million tonnes
in 1979-80. Production of food grains
then rose continuously to 252 million
tonnes in 2015-16 and touched 272
million tonnes in 2016–17.”
In this statement, you can observe
that the food grains production in
different years does not remain the
same. It varies from year to year and
CHAPTER
2
2020-21
10 STATISTICS FOR ECONOMICS
from crop to crop. As these values vary,
they are called variable. The variables
are generally represented by the letters
X, Y or Z. Each value of a variable is an
observation. For example, the food
grain production in  India varies
between 108 million tonnes in 1970–
71  to 272 million tonnes  in 2016-17
as shown  in the following table. The
years are represented by variable X and
the production of food grain in India
(in million tonnes) is represented by
variable Y.
TABLE 2.1
Production of Food Grain in India
(Million Tonnes)
     X Y
1970–71 108
1978–79 132
1990–91 176
1997–98 194
2001–02 212
2015-16 252
2016-17 272
Here, the values of these variables
X and Y are the ‘data’, from which we
can obtain information about the
production of food grains in India. To
know the fluctuations in food grains
production, we need the ‘data’ on the
production of food grains in India for
various years. ‘Data’ is a tool, which
helps in understanding problems by
providing information.
You must be wondering where do
‘data’ come from and how do we collect
these? In the following sections we will
discuss the types of data, method and
instruments of data collection and
sources of obtaining data.
2. WHAT ARE THE SOURCES OF DATA?
Statistical data can be obtained from
two sources. The researcher may
collect the data by conducting an
enquiry. Such  data are called Primary
Data, as they are based on first hand
information. Suppose, you want to
know about the popularity of a filmstar
among school students. For  this, you
will have to enquire from a large
number of school students, by asking
questions from them to collect the
desired information. The data you get,
is an example of primary data.
If the data have been collected and
processed (scrutinised and tabulated)
by some other agency, they are called
Secondary Data.  They can be obtained
either from published sources such as
government reports, documents,
newspapers, books written by
economists or from any other source,
for example, a website. Thus, the data
are primary to the source that collects
and processes them for the first time
and secondary for all sources that later
use such data. Use of secondary data
saves time and cost. For example, after
collecting the data on the popularity of
the filmstar among students, you
publish a report. If somebody uses the
data collected by you for a similar
study, it becomes secondary data.
3. HOW DO WE COLLECT THE DATA?
Do you know how a manufacturer
decides about a product or how a
political party decides about a
candidate? They conduct a survey by
2020-21
COLLECTION OF DATA 11
asking questions about a particular
product or candidate from a large
group of people. The purpose of surveys
is to describe some characteristics like
price, quality, usefulness (in case of the
product) and popularity, honesty,
loyalty (in case of the candidate). The
purpose of the survey is to collect data.
Survey is a method of gathering
information from individuals.
Preparation of Instrument
The most common type of instrument
used in surveys is questionnaire/
interview schedule. The questionnaire
is either self administered by the
respondent or administered by the
researcher (enumerator) or trained
investigator. While preparing the
questionnaire/interview schedule,
you should keep in mind the following
points;
• The questionnaire should not be
too long. The number of questions
should be as minimum as
possible.
• The questionnaire should be easy
to understand and avoid
ambiguous or difficult words.
• The questions should be arranged
in an order such that the person
answering should feel
comfortable.
• The series of questions should
move from general to specific. The
questionnaire should start from
general questions and proceed to
more specific ones. For example:
Poor Q
(i) Is increase in electricity charges
justified?
(ii) Is the electricity supply in your
locality regular?
Good Q
(i) Is the electricity supply in your
locality regular?
(ii) Is increase in electricity charges
justified?
• The questions should be precise
and clear. For example,
Poor Q
What percentage of your income do you
spend on clothing in order to look
presentable?
Good Q
What percentage of your income do you
spend on clothing?
• The questions should not be
ambiguous. They should enable
the respondents to answer quickly,
correctly and clearly. For example:
Poor Q
Do you spend a lot of money on books
in a month?
Good Q
(Tick mark the appropriate option)
How much do you spend on books in
a month?
(i) Less than Rs 200
(ii) Rs 200–300
(iii)Rs 300–400
(iv) More than Rs 400
• The question should not use double
negatives. The questions starting
with “Wouldn’t you” or “Don’t you”
should be avoided, as they may lead
to biased responses. For example:
2020-21
Page 4


Collection of Data
1. INTRODUCTION
In the previous chapter, you have read
about what is economics. You also
studied about the role and importance
of statistics in economics. In this
Studying this chapter should
enable you to:
• understand the meaning and
purpose of data collection;
• distinguish between primary and
secondary sources;
• know the mode of collection of data;
• distinguish between Census and
Sample Surveys;
• be familiar with the techniques of
sampling;
• know about some important sources
of secondary data.
chapter, you will study the sources of
data and the mode of data collection.
The purpose of collection of data is to
show evidence for reaching a sound and
clear solution to a problem.
In economics, you often come
across a statement like this,
“After many fluctuations the output
of food grains rose to 132 million tonnes
in 1978-79 from 108 million tonnes in
1970-71, but fell to 108 million tonnes
in 1979-80. Production of food grains
then rose continuously to 252 million
tonnes in 2015-16 and touched 272
million tonnes in 2016–17.”
In this statement, you can observe
that the food grains production in
different years does not remain the
same. It varies from year to year and
CHAPTER
2
2020-21
10 STATISTICS FOR ECONOMICS
from crop to crop. As these values vary,
they are called variable. The variables
are generally represented by the letters
X, Y or Z. Each value of a variable is an
observation. For example, the food
grain production in  India varies
between 108 million tonnes in 1970–
71  to 272 million tonnes  in 2016-17
as shown  in the following table. The
years are represented by variable X and
the production of food grain in India
(in million tonnes) is represented by
variable Y.
TABLE 2.1
Production of Food Grain in India
(Million Tonnes)
     X Y
1970–71 108
1978–79 132
1990–91 176
1997–98 194
2001–02 212
2015-16 252
2016-17 272
Here, the values of these variables
X and Y are the ‘data’, from which we
can obtain information about the
production of food grains in India. To
know the fluctuations in food grains
production, we need the ‘data’ on the
production of food grains in India for
various years. ‘Data’ is a tool, which
helps in understanding problems by
providing information.
You must be wondering where do
‘data’ come from and how do we collect
these? In the following sections we will
discuss the types of data, method and
instruments of data collection and
sources of obtaining data.
2. WHAT ARE THE SOURCES OF DATA?
Statistical data can be obtained from
two sources. The researcher may
collect the data by conducting an
enquiry. Such  data are called Primary
Data, as they are based on first hand
information. Suppose, you want to
know about the popularity of a filmstar
among school students. For  this, you
will have to enquire from a large
number of school students, by asking
questions from them to collect the
desired information. The data you get,
is an example of primary data.
If the data have been collected and
processed (scrutinised and tabulated)
by some other agency, they are called
Secondary Data.  They can be obtained
either from published sources such as
government reports, documents,
newspapers, books written by
economists or from any other source,
for example, a website. Thus, the data
are primary to the source that collects
and processes them for the first time
and secondary for all sources that later
use such data. Use of secondary data
saves time and cost. For example, after
collecting the data on the popularity of
the filmstar among students, you
publish a report. If somebody uses the
data collected by you for a similar
study, it becomes secondary data.
3. HOW DO WE COLLECT THE DATA?
Do you know how a manufacturer
decides about a product or how a
political party decides about a
candidate? They conduct a survey by
2020-21
COLLECTION OF DATA 11
asking questions about a particular
product or candidate from a large
group of people. The purpose of surveys
is to describe some characteristics like
price, quality, usefulness (in case of the
product) and popularity, honesty,
loyalty (in case of the candidate). The
purpose of the survey is to collect data.
Survey is a method of gathering
information from individuals.
Preparation of Instrument
The most common type of instrument
used in surveys is questionnaire/
interview schedule. The questionnaire
is either self administered by the
respondent or administered by the
researcher (enumerator) or trained
investigator. While preparing the
questionnaire/interview schedule,
you should keep in mind the following
points;
• The questionnaire should not be
too long. The number of questions
should be as minimum as
possible.
• The questionnaire should be easy
to understand and avoid
ambiguous or difficult words.
• The questions should be arranged
in an order such that the person
answering should feel
comfortable.
• The series of questions should
move from general to specific. The
questionnaire should start from
general questions and proceed to
more specific ones. For example:
Poor Q
(i) Is increase in electricity charges
justified?
(ii) Is the electricity supply in your
locality regular?
Good Q
(i) Is the electricity supply in your
locality regular?
(ii) Is increase in electricity charges
justified?
• The questions should be precise
and clear. For example,
Poor Q
What percentage of your income do you
spend on clothing in order to look
presentable?
Good Q
What percentage of your income do you
spend on clothing?
• The questions should not be
ambiguous. They should enable
the respondents to answer quickly,
correctly and clearly. For example:
Poor Q
Do you spend a lot of money on books
in a month?
Good Q
(Tick mark the appropriate option)
How much do you spend on books in
a month?
(i) Less than Rs 200
(ii) Rs 200–300
(iii)Rs 300–400
(iv) More than Rs 400
• The question should not use double
negatives. The questions starting
with “Wouldn’t you” or “Don’t you”
should be avoided, as they may lead
to biased responses. For example:
2020-21
12 STATISTICS FOR ECONOMICS
Poor Q
Don’t you think smoking should be
prohibited?
Good Q
Do you think smoking should be
prohibited?
• The question should not be a
leading question, which gives a
clue about how the respondent
should answer. For example:
Poor Q
How do you like the flavour of this high-
quality tea?
Good Q
How do you like the flavour of this tea?
• The question should not indicate
alternatives to the answer. For
example:
Poor Q
Would you like to do a job after college
or be a housewife?
Good Q
What would you like to do after college ?
The questionnaire may consist of
closed-ended (or structured) questions
or open-ended (or unstructured)
questions. The above question about
what a student wants do after college
is an open-ended question.
Closed-ended or structured
questions can either be a two-way
question or a multiple choice question.
When there are only two possible
answers, ‘yes’ or ‘no’, it is called a two-
way question.
When there is a possibility of more
than two options of answers, multiple
choice questions are more appropriate.
Example,
Q. Why did you sell your land?
(i) To pay off the debts.
(ii) To finance children’s education.
(iii) To invest in another property.
(iv) Any other (please specify).
Closed-ended questions are easy
to use, score and to codify for analysis,
because all respondents can choose
from the given options. But they are
difficult to write as the alternatives
should be clearly written to represent
both sides of the issue. There is also a
possibility that an individual’s true
response is not present among the
options given. For this, the choice of
‘Any Other’ is provided, where the
respondent can write a response, which
was not anticipated by the researcher.
Moreover, another limitation of
multiple-choice questions is that they
tend to restrict the answers by
providing alternatives, without which
the respondents may have answered
differently.
Open-ended questions allow for
more individualised responses, but
they are difficult to interpret and hard
to score, since there are a lot of
variations in the responses. Example,
Q.What is your view about
globalisation?
Mode of Data Collection
Have you ever come across a television
show in which reporters ask questions
from children, housewives or general
public regarding their examination
performance or a brand of soap or a
2020-21
Page 5


Collection of Data
1. INTRODUCTION
In the previous chapter, you have read
about what is economics. You also
studied about the role and importance
of statistics in economics. In this
Studying this chapter should
enable you to:
• understand the meaning and
purpose of data collection;
• distinguish between primary and
secondary sources;
• know the mode of collection of data;
• distinguish between Census and
Sample Surveys;
• be familiar with the techniques of
sampling;
• know about some important sources
of secondary data.
chapter, you will study the sources of
data and the mode of data collection.
The purpose of collection of data is to
show evidence for reaching a sound and
clear solution to a problem.
In economics, you often come
across a statement like this,
“After many fluctuations the output
of food grains rose to 132 million tonnes
in 1978-79 from 108 million tonnes in
1970-71, but fell to 108 million tonnes
in 1979-80. Production of food grains
then rose continuously to 252 million
tonnes in 2015-16 and touched 272
million tonnes in 2016–17.”
In this statement, you can observe
that the food grains production in
different years does not remain the
same. It varies from year to year and
CHAPTER
2
2020-21
10 STATISTICS FOR ECONOMICS
from crop to crop. As these values vary,
they are called variable. The variables
are generally represented by the letters
X, Y or Z. Each value of a variable is an
observation. For example, the food
grain production in  India varies
between 108 million tonnes in 1970–
71  to 272 million tonnes  in 2016-17
as shown  in the following table. The
years are represented by variable X and
the production of food grain in India
(in million tonnes) is represented by
variable Y.
TABLE 2.1
Production of Food Grain in India
(Million Tonnes)
     X Y
1970–71 108
1978–79 132
1990–91 176
1997–98 194
2001–02 212
2015-16 252
2016-17 272
Here, the values of these variables
X and Y are the ‘data’, from which we
can obtain information about the
production of food grains in India. To
know the fluctuations in food grains
production, we need the ‘data’ on the
production of food grains in India for
various years. ‘Data’ is a tool, which
helps in understanding problems by
providing information.
You must be wondering where do
‘data’ come from and how do we collect
these? In the following sections we will
discuss the types of data, method and
instruments of data collection and
sources of obtaining data.
2. WHAT ARE THE SOURCES OF DATA?
Statistical data can be obtained from
two sources. The researcher may
collect the data by conducting an
enquiry. Such  data are called Primary
Data, as they are based on first hand
information. Suppose, you want to
know about the popularity of a filmstar
among school students. For  this, you
will have to enquire from a large
number of school students, by asking
questions from them to collect the
desired information. The data you get,
is an example of primary data.
If the data have been collected and
processed (scrutinised and tabulated)
by some other agency, they are called
Secondary Data.  They can be obtained
either from published sources such as
government reports, documents,
newspapers, books written by
economists or from any other source,
for example, a website. Thus, the data
are primary to the source that collects
and processes them for the first time
and secondary for all sources that later
use such data. Use of secondary data
saves time and cost. For example, after
collecting the data on the popularity of
the filmstar among students, you
publish a report. If somebody uses the
data collected by you for a similar
study, it becomes secondary data.
3. HOW DO WE COLLECT THE DATA?
Do you know how a manufacturer
decides about a product or how a
political party decides about a
candidate? They conduct a survey by
2020-21
COLLECTION OF DATA 11
asking questions about a particular
product or candidate from a large
group of people. The purpose of surveys
is to describe some characteristics like
price, quality, usefulness (in case of the
product) and popularity, honesty,
loyalty (in case of the candidate). The
purpose of the survey is to collect data.
Survey is a method of gathering
information from individuals.
Preparation of Instrument
The most common type of instrument
used in surveys is questionnaire/
interview schedule. The questionnaire
is either self administered by the
respondent or administered by the
researcher (enumerator) or trained
investigator. While preparing the
questionnaire/interview schedule,
you should keep in mind the following
points;
• The questionnaire should not be
too long. The number of questions
should be as minimum as
possible.
• The questionnaire should be easy
to understand and avoid
ambiguous or difficult words.
• The questions should be arranged
in an order such that the person
answering should feel
comfortable.
• The series of questions should
move from general to specific. The
questionnaire should start from
general questions and proceed to
more specific ones. For example:
Poor Q
(i) Is increase in electricity charges
justified?
(ii) Is the electricity supply in your
locality regular?
Good Q
(i) Is the electricity supply in your
locality regular?
(ii) Is increase in electricity charges
justified?
• The questions should be precise
and clear. For example,
Poor Q
What percentage of your income do you
spend on clothing in order to look
presentable?
Good Q
What percentage of your income do you
spend on clothing?
• The questions should not be
ambiguous. They should enable
the respondents to answer quickly,
correctly and clearly. For example:
Poor Q
Do you spend a lot of money on books
in a month?
Good Q
(Tick mark the appropriate option)
How much do you spend on books in
a month?
(i) Less than Rs 200
(ii) Rs 200–300
(iii)Rs 300–400
(iv) More than Rs 400
• The question should not use double
negatives. The questions starting
with “Wouldn’t you” or “Don’t you”
should be avoided, as they may lead
to biased responses. For example:
2020-21
12 STATISTICS FOR ECONOMICS
Poor Q
Don’t you think smoking should be
prohibited?
Good Q
Do you think smoking should be
prohibited?
• The question should not be a
leading question, which gives a
clue about how the respondent
should answer. For example:
Poor Q
How do you like the flavour of this high-
quality tea?
Good Q
How do you like the flavour of this tea?
• The question should not indicate
alternatives to the answer. For
example:
Poor Q
Would you like to do a job after college
or be a housewife?
Good Q
What would you like to do after college ?
The questionnaire may consist of
closed-ended (or structured) questions
or open-ended (or unstructured)
questions. The above question about
what a student wants do after college
is an open-ended question.
Closed-ended or structured
questions can either be a two-way
question or a multiple choice question.
When there are only two possible
answers, ‘yes’ or ‘no’, it is called a two-
way question.
When there is a possibility of more
than two options of answers, multiple
choice questions are more appropriate.
Example,
Q. Why did you sell your land?
(i) To pay off the debts.
(ii) To finance children’s education.
(iii) To invest in another property.
(iv) Any other (please specify).
Closed-ended questions are easy
to use, score and to codify for analysis,
because all respondents can choose
from the given options. But they are
difficult to write as the alternatives
should be clearly written to represent
both sides of the issue. There is also a
possibility that an individual’s true
response is not present among the
options given. For this, the choice of
‘Any Other’ is provided, where the
respondent can write a response, which
was not anticipated by the researcher.
Moreover, another limitation of
multiple-choice questions is that they
tend to restrict the answers by
providing alternatives, without which
the respondents may have answered
differently.
Open-ended questions allow for
more individualised responses, but
they are difficult to interpret and hard
to score, since there are a lot of
variations in the responses. Example,
Q.What is your view about
globalisation?
Mode of Data Collection
Have you ever come across a television
show in which reporters ask questions
from children, housewives or general
public regarding their examination
performance or a brand of soap or a
2020-21
COLLECTION OF DATA 13
political party? The purpose of asking
questions is to do a survey for collection
of data. There are three basic ways of
collecting data: (i) Personal Interviews,
(ii) Mailing (questionnaire) Surveys,
and (iii) Telephone Interviews.
Personal Interviews
This method is
used when the
researcher has
access to all the
members. The
researcher (or
investigator)
conducts face-
to-face interviews with the respondents.
Personal interviews are preferred
due to various reasons. Personal
contact is made between the
respondent and the interviewer. The
interviewer has the opportunity of
explaining the study and answering the
queries of respondents. The interviewer
can request the respondent to expand
on answers that are particularly
important. Misinterpretation and
misunderstanding can be avoided.
Watching the reactions of  respondents
can provide supplementary
information.
Personal interview has some
demerits too. It is expensive, as it
requires trained interviewers. It takes
longer time to complete the survey.
Presence of the researcher may inhibit
respondents from saying what they
really think.
Mailing Questionnaire
When the data in a survey are collected
by mail, the questionnaire is sent to
each individual by mail
with a request to
complete and return it
by a given date. The
advantages of this
method are that, it is
less expensive. It allows the researcher
to have access to people in remote
areas too, who might be difficult to
reach in person or by telephone. It does
not allow influencing of the respondents
by the interviewer. It also permits the
respondents to take sufficient time to
give thoughtful answers to the
questions.
These days online surveys or
surveys through short messaging
service, i.e., SMS are popular. Do you
know how an online survey is
conducted?
The disadvantages of mail survey
are that there is less opportunity to
provide assistance in clarifying
instructions, so there is a possibility of
misunderstanding the questions.
Mailing is also likely to produce low
response rates due to certain factors,
such as returning the questionnaire
without completing it, not returning the
questionnaire at all, loss of
questionnaire in the mail itself, etc.
Telephone Interviews
In a telephone
interview, the
investigator asks
questions over the
2020-21