Class Statistic
11 s
Collection of
Data
Methods
Sources
of
of
Collecting
Data
Data
Data Statistics means data or quantitative
information capable of some
meaningful conclusions. In other words,
in data, we include that information
which is capable of numerical
expression.
Let us recall some examples of data :
That there are eight sugar mills in Haryana compared to 20
in Punjab.
20 per cent of the people in the working age group are unemployed
in India compared to only 2 per cent in the USA.
Of the total cattle population of the world, 50 per cent belongs
to India.
Sources of
Data
There are two sources of
data
Primary Secondary
Source Source
Primary It implies collection of data from
Source its source of origin.
of Data It offers you first-hand quantitative
information relating to your
statistical study.
It implies a collection of data from some Secondary
agency or institution which already Source of
happens to have collected the data Data
through statistical survey.
It does not offer you first-hand
information relating to your statistical
study.
Primary data refers to the data collected by the
Primary investigator for his own purpose, for the first time,
Data from beginning to end called primary data. These
are collected from the source of origin. In the
words of Wessel, “Data originally collected in the
process of investigation are known as primary
data.”
Secondary data refers to the data collected by
Secondary other persons are called secondary data. These
Data data are called second-hand data. Since these
data have already been collected by somebody
else, these are available in the form of published
or unpublished reports.
The difference between Primary and Secondary Data are
: Basis Primary Data Secondary Data
Primary data is original Secondary data is not original
because it is collected by as the investigator uses data
Originality the investigator from the collected by some other person
source of their origin. or agency.
It takes more time to collect Secondary data collection
Time primary data. involves
less time.
It is cheaper as data is
It is costly in terms of
Cost money and the effort
collected from published or
unpublished sources.
involved.
Primary data is highly Secondary data may not suit the
reliable and suitable to purpose of the investigation and
Suitability the enquiry as the therefore, needs to be adjusted
investigator himself to suit the objective of the
collects it. study.
Modes of Collection of
Data
(Primary Data)
ILS IQS
DPI IOI Information Information
Direct Personal Indirect Oral from Local through
Investigation Investigation Sources or Questionnaires
Correspondents & Schedules
Mailing Enumerator’s
Method Method
Direct Personal
Investigation
According to this method, data is collected by the
investigator personally from persons who are the
subject of enquiry. He interviews everyone who is
in a position to supply the information he
requires.
Suitability
This method of collecting primary data is suitable
particularly when :
1) The field of investigation is limited or not very
large;
2) A greater degree of originality of the data is
Merits of Direct Personal Investigation
1) Originality : Data have a high degree of originality.
2) Accuracy : Data are fairly accurate when personally
collected.
3) Reliability : Because the information is collected by the
investigator himself, the reliability of the data is not
doubted.
4) Uniformity : There is a fair degree of uniformity in the
data collected by the investigator himself from
the informants. It facilitates comparison.
5) Elastic : This method is fairly elastic
Demerits of Direct Personal
Investigation
1) Difficult to cover wide areas : Direct personal
investigation becomes very difficult when the areas of the
study are very wide.
2) Personal Bias : This method is highly prone to the personal
bias of the investigator. As a result, the data may lose
credibility.
3) Costly : This method is very expensive in
terms of the time, money and effort
involved.
4) Limited Coverage : In this method, the area of
investigation is generally small. The results are,
Indirect Oral Investigation
Indirect oral investigation is the method by which information is obtained not
from the persons regarding whom the information is needed. It is collected
orally from other persons who are expected to possess the necessary
information. These other persons are known as witnesses.
For example, by this method, the data on the economic conditions of the
workers may be collected from their employers rather than the workers
themselves.
Suitability
This method is suitable, particularly when :
1) The field of investigation is relatively large.
2) It is not possible to have direct contact with the concerned informants.
3) The concerned informants are not capable of giving information because
of their ignorance or illiteracy.
4) Investigation is so complex in nature that only experts can give
Merits of Indirect Oral
Investigation
1) Wide Coverage : This method can be applied even
when the field of investigation is very wide.
2) Less Expensive : This is relatively a less expensive
method as compared to Direct Personal
Investigation.
3) Free from Bias : This method is relatively free from
the personal bias of the investigator.
4) Simple : This is relatively a
simple approach to data
Demerits of Indirect Oral
Investigation
1) Less Accurate : The data collected by this method
are relatively less accurate. This is because the
information is obtained from persons other than
the concerned informants.
2) Biased : There is the possibility of
personal bias of the witnesses giving
information.
3) Doubt Conclusion : This method
may lead to doubtful conclusions
Information from Local Sources or
Correspondents
Under this method, the investigator appoints local
persons or correspondents at different places.
They collect information in their own way and
furnish the same to the investigator.
Suitability
This method is suitable, particularly when :
1) Regular continuous information is needed.
2) The area of investigation is large.
3) The information is to be used by journals, magazines, radio, TV, etc.
and
4) A very high degree of accuracy of information is not required.
Merits of Information from Local Sources or
Correspondents
1) Economical : This method is quite
economical in terms of time, money or
efforts involved.
2) Wide Coverage : This method allows a
fairly wide coverage of the
investigation.
3) Continuity : The correspondents keep
on supplying almost regular
information.
4) Suitable for a Special Purpose : This method is
Demerits of Information from Local Sources or
Correspondents
1) Lack of Originality : Originality of data is sacrificed
owing to the lack of personal contact with
2) respondents.
Lack of Uniformity : There is a lack of
uniformity of data. This is because data is
collected by several correspondents.
3) Less Accurate : The data collected
by this method are not very
accurate.
4) Delay in Collection : Generally, there is a delay in
the collection of information through this method.
Information through Questionnaires &
Schedules
Under this method, the investigator prepares a
questionnaire to keep in view the objective of the enquiry.
There are two ways of
collecting information based on
the questionnaire
Mailing Enumerator’s
Method Metho
d
Under this method, questionnaires are
Mailing
mailed to the informants.
Metho A letter is attached with the questionnaire
d giving the purpose of the enquiry. It is also
assured that the information would be kept
secret. The informant notes the answers
against the questions and returns the
completed questionnaire to the investigator.
Suitability
This method is most suited when :
1) The area of the study is very wide, and
2) The informants are educated.
1) Economical : This method is economical in terms of time, money
and efforts involved.
Merits 2) Original : This method is original and therefore, fairly reliable.
of This is because the information is duly supplied by
the concerned persons themselves.
Mailing 3) Wide Coverage : This method allows wide
Method coverage of the area of study.
1) Lack of Interest : Generally, the informants do not take interest
in questionnaires and fail to return the questionnaires.
2) Lack of Flexibility : This method lacks flexibility.
Demerits When questions are not properly replied, these
of cannot be changed to obtain the required information.
3) Limited Use : This method has limited use because the
Mailing questionnaires can be answered only by educated informants.
4) Biased : If the informants are biased, then the information will
Method also be biased.
Under this method, a questionnaire is prepared
Enumerator’s according to the purpose of enquiry. The
Method enumerator himself approaches the informant with the
questionnaire. The questionnaires which are filled by the
enumerator by putting questions are called schedules.
Enumerators are those persons who help the
investigators in collecting the data.
The Enumerators are given the training to fill the
schedules and put the questions intelligently to
obtain accurate information.
Suitability
This method is mostly used :
1) Field of investigation is large.
2) The investigation needs specialized and skilled investigators, and
3) The investigators are well versed in the local language and cultural norms
of the informants.
1) Wide Coverage : This method is capable of wide coverage in
Merits of terms of the area involved.
Enumerator’s 2) Accuracy : There is a fair degree of accuracy in the results. This
Method is
because investigations are done by specialized enumerators.
3) Personal Contact : Unlike in the case of mailing
questionnaires, there is personal contact with the informants
in this method.
4) Completeness : Schedules have the merit of completeness
1) Expensive
because : This is a very expensive method of investigation
Demerits of because
these areoffilled
the involvement of trainedthemselves.
in by the enumerators investigators.
Enumerator's 2) Availability of Enumerators : Competent enumerators may not
be available. The accuracy of the information accordingly
Method
suffers.
3) Time-consuming : Enumerators may need specialized training for
a particular investigation. The process of the investigation thus
becomes time-consuming.
4) Partial : If the enumerators are biased then the data will not
be accurate.
Qualities of A Good Questionnaire
1) Limited Number of questions :
The number of questions in a questionnaire should be as limited as possible.
Questions should be only related to the purpose of the enquiry.
2) Simplicity :
The language of the questions should be simple, lucid and clear. Questions
should be short, not long or complex. Mathematical questions must be avoided.
3) Proper order of the questions :
Questions must be placed in a proper order.
4) No undesirable questions :
Undesirable questions or personal questions must be avoided. The questions should not offend the informants.
5) Non-Controversial :
Questions should be such as can be answered impartially. No controversial questions should be asked.
6) Calculations :
Questions involving calculations by the respondents must be avoided. Investigator himself must do the calculation job.
Collection of
Secondary Data
Sources of
Secondary
Data
Published Unpublished
sources sources
Published
1) Government Publications :
Sources
Ministries of the central and state governments in India publish a variety of statistics as their routine activity. Some
of the notable government publications on statistics are the statistical abstract of India, the Annual Survey of
Industries, etc.
2) Semi-government Publications :
Semi-government bodies publish data relating to education, health, births and deaths.
3) Publications of Trade Associations :
Some of the big trade associations, through their statistical and research
divisions, collect and publish data on various aspects of trading activity
4) Publications of Research Institutions :
Various universities and research institutions publish information as findings of their research activities
5) Journals and Papers :
Many newspapers such as The Economic Times as well as magazines such as Commerce, and Facts for You also Supply a
large variety of statistical information.
6) Publications of Research Scholars :
Individual research scholars also sometimes publish their research work containing some useful statistical information.
7) International Publications :
International organizations such as UNO, IMF, World Bank, ILO, and foreign governments etc., also publish a lot
of statistical information. These are used as secondary data.
Unpublished
Sources
These data are collected by government organizations and others, generally for their self-use or office record.
These data are not published. This unpublished numerical information may, however, be used as secondary data.
To assess the reliability, suitability and adequacy of the data, the following points must be kept in mind.
1) Ability of the Collecting Organization :
One should check the ability of the organization which initially collected the data.
2) Objective and Scope :
Data should be used only if the objective and scope of the study as undertaken
earlier match with the objective and scope of the present study.
3) Method of Collection :
The method of collection of data by the original investigator should also be noted.
4) Time and Conditions of Collection :
One should also make sure of the period of investigation as well as the conditions of
investigations.
5) Definition of the Unit :
One should also make sure that the units of measurement used in the initial collection of data are the
same as those adopted in the present study.
6) Accuracy :
Accuracy of the data should also be checked. If the available data do not conform to the required degree
of accuracy these should be discarded.
Two important sources of Secondary
Data
1) Census of India : :
Census of India is a decennial publication of the government of India. It relates to population size
and the various aspect of demographic changes in India.
Broadly, it includes statistical information on the following parameters :
a) Size, growth rate and distribution of population in India.
b) Density of population
c) Sex composition of the population
d) State of literacy
2) Reports and publications of the National Sample Survey Office (NSSO) :
NSSO is a government organization under the Ministry of Statistics and Programme
Implementation.
This organization conducts regular sample surveys to collect basic statistical information relating to
a variety of economic activities in rural as well as urban parts of the country.
Reports and publications of NSSO offer statistical information on the
following parameters of economic change :
a) Land and Livestock holdings.
b) Housing conditions and migration with special emphasis on slum dwellers.
c) Employment and unemployment status in India.
d) Sources of household income in India.
e) Employment and Unemployment status in India.
