When a population from which a sample is to be selected does
not comprise a homogeneous group, stratified sampling technique is
generally employed for obtaining a representative sample. Under stratified
sampling, the population is divided into many sub-populations in such a
manner that they are individually more homogeneous than the rest of the
total population. Then, items are selected from each stratum to form a
sample. As each stratum is more homogeneous than the remaining total
population, the researcher is able to obtain a more precise estimate for each
stratum and by estimating each of the component parts more accurately;
he/she is able to obtain a better estimate of the whole. In sum, stratified
sampling method yields more reliable and detailed information.
(iii) Cluster Sampling:
When the total area of research interest is large, a convenient way
in which a sample can be selected is to divide the area into a number of
smaller non-overlapping areas and then randomly selecting a number of
such smaller areas. In the process, the ultimate sample would consist of all
the units in these small areas or clusters. Thus in cluster sampling, the total
population is sub-divided into numerous relatively smaller subdivisions,
which in themselves constitute clusters of still smaller units. And then,
some of such clusters are randomly chosen for inclusion in the overall
sample.
(iv) Area Sampling:
When clusters are in the form of some geographic subdivisions,
then cluster sampling is termed as area sampling. That is, when the
primary sampling unit represents a cluster of units based on geographic
area, the cluster designs are distinguished as area sampling. The merits
and demerits of cluster sampling are equally applicable to area sampling.
(v)
Multi-Stage Sampling:
A further development of the principle of cluster sampling is
multi-stage sampling. When the researcher desires to investigate the
working efficiency of nationalized banks in India and a sample of few
39
banks is required for this purpose, the first stage would be to select large
primary sampling unit like the states in the country. Next, certain districts
may be selected and all banks interviewed in the chosen districts. This
represents a two-stage sampling design, with the ultimate sampling units
being clusters of districts.
On the other hand, if instead of taking census of all banks within
the selected districts, the researcher chooses certain towns and interviews
all banks in it, this would represent three-stage sampling design. Again,
if instead of taking a census of all banks within the selected towns, the
researcher randomly selects sample banks from each selected town, then
it represents a case of using a four-stage sampling plan. Thus, if the
researcher selects randomly at all stages, then it is called as multi-stage
random sampling design.
(vi) Sampling With Probability Proportional To Size:
When the case of cluster sampling units does not have exactly or
approximately the same number of elements, it is better for the researcher
to adopt a random selection process, where the probability of inclusion
of each cluster in the sample tends to be proportional to the size of the
cluster. For this, the number of elements in each cluster has to be listed,
irrespective of the method used for ordering it. Then the researcher should
systematically pick the required number of elements from the cumulative
totals. The actual numbers thus chosen would not however reflect the
individual elements, but would indicate as to which cluster and how many
from them are to be chosen by using simple random sampling or systematic
sampling. The outcome of such sampling is equivalent to that of simple
random sample. The method is also less cumbersome and is also relatively
less expensive.
Thus, a researcher has to pass through various stages of conducting
research once the problem of interest has been selected. Research
methodology familiarizes a researcher with the complex scientific methods
of conducting research, which yield reliable results that are useful to
policy-makers, government, industries etc. in decision-making.
40
End of Chapter Questions:[IMPORTANT QUESTIONS FOR EXAM]
1. Define research.
2. What are the objectives of research?
3. State the significance of research.
4. What is the importance of knowing how to do research?
5. Briefly outline research process.
6. Highlight the different research approaches.
7. Discuss the qualities of a researcher.
8. Explain the different types of research.
9. What is a research problem?
10. Outline the features of research design.
11. Discuss the features of a good research design.
12. Describe the different types of research design.
13. Explain the significance of research design.
14. What is a case study?
15. Discuss the criteria for evaluating case study.
16. Define hypothesis.
17. What are the characteristic features of a hypothesis?
18. Distinguish between null and alternative hypothesis.
19. Differentiate type i error and type ii error.
20. How is a hypothesis tested?
21. Define the concept of sampling design.
41
22. Describe the steps involved in sampling design.
23. Discuss the criteria for selecting a sampling procedure.
24. Distinguish between probability and non-probability sampling.
25. How is a random sample selected?
26. Explain complex random sampling designs.
***
42CHAPTER—II
Lesson 1: Data Collection & Sources Of Data
1. Primary Data, Secondary Data
2. Investigation
3. Indirect Oral Methods Of Collecting Primary Data
4. Direct Personal Interviews
5. Information Received Through Local Agencies
6. Mailed Questionnaire Method
7. Schedules Sent Through Enumerators
Meaning of primary data, Secondary data,Preliminaries of data
collection,Method of data collection,Methods of collecting primary
data ,Usefulness of primary data ,Merits and demerits of
different methods of primary data collection
Precautions while collecting primary data.
Secondary data collection
Introduction:
It is important for a researcher to know the sources of data which
he requires for different purposes. Data are nothing but the information.
There are two sources of information or data they are - Primary and
Secondary data. The data are name after the source. Primary data refers
to the data collected for the first time, whereas secondary data refers to
the data that have already been collected and used earlier by somebody
or some agency. For example, the statistics collected by the Government
43
of India relating to the population is primary data for the Government of
India since it has been collected for the first time. Later when the same
data are used by a researcher for his study of a particular problem, then
the same data become the secondary data for the researcher. Both the
sources of information have their merits and demerits. The selection of
a particular source depends upon the (a) purpose and scope of enquiry,
(b) availability of time, (c) availability of finance, (d) accuracy required,
(e) statistical tools to be used, (f) sources of information (data), and (g)
method of data collection.
(a)
Purpose And Scope Of Enquiry:
The purpose and scope of data collection or survey should be
clearly set out at the very beginning. It requires the clear statement of the
problem indicating the type of information which is needed and the use for
which it is needed. If for example, the researcher is interested in knowing
the nature of price change over a period of time, it would be necessary to
collect data of commodity prices. It must be decided whether it would be
helpful to study wholesale or retail prices and the possible uses to which
such information could be put. The objective of an enquiry may be either
to collect specific information relating to a problem or adequate data to
test a hypothesis. Failure to set out clearly the purpose of enquiry is bound
to lead to confusion and waste of resources.
After the purpose of enquiry has been clearly defined, the next step
is to decide about the scope of the enquiry. Scope of the enquiry means the
coverage with regard to the type of information, the subject-matter and
geographical area. For instance, an enquiry may relate to India as a whole
or a state or an industrial town wherein a particular problem related to a
particular industry can be studied.
(b)
Availability Of Time:
The investigation should be carried out within a reasonable period
of time, failing which the information collected may become outdated,
and would have no meaning at all. For instance, if a producer wants to
know the expected demand for a product newly launched by him and the
result of the enquiry that the demand would be meager takes two years
to reach him, then the whole purpose of enquiry would become useless
44
because by that time he would have already incurred a huge loss. Thus, in
this respect the information is quickly required and hence the researcher
has to choose the type of enquiry accordingly.
(c)
Availability Of Resources:
The investigation will greatly depend on the resources available like
number of skilled personnel, the financial position etc. If the number of
skilled personnel who will carry out the enquiry is quite sufficient and the
availability of funds is not a problem, then enquiry can be conducted over
a big area covering a good number of samples, otherwise a small sample
size will do.
(d)
The Degree Of Accuracy Desired:
Deciding the degree of accuracy required is a must for the
investigator, because absolute accuracy in statistical work is seldom
achieved. This is so because (i) statistics are based on estimates, (ii) tools
of measurement are not always perfect and (iii) there may be unintentional
bias on the part of the investigator, enumerator or informant. Therefore, a
desire of 100% accuracy is bound to remain unfulfilled. Degree of accuracy
desired primarily depends upon the object of enquiry. For example, when
we buy gold, even a difference of 1/10th gram in its weight is significant,
whereas the same will not be the case when we buy rice or wheat. However,
the researcher must aim at attaining a higher degree of accuracy, otherwise
the whole purpose of research would become meaningless.
(e)
Statistical Tools To Be Used:
A well defined and identifiable object or a group of objects with
which the measurements or counts in any statistical investigation are
associated is called a statistical unit. For example, in socio-economic survey
the unit may be an individual, a family, a household or a block of locality.
A very important step before the collection of data begins is to define
clearly the statistical units on which the data are to be collected. In number
of situations the units are conventionally fixed like the physical units of
measurement, such as meters, kilometers, quintals, hours, days, weeks etc.,
which are well defined and do not need any elaboration or explanation.
However, in many statistical investigations, particularly relating to socio-
45
economic studies, arbitrary units are used which must be clearly defined.
This is a must because in the absence of a clear cut and precise definition of
the statistical units, serious errors in the data collection may be committed
in the sense that we may collect irrelevant data on the items, which should
have, in fact, been excluded and omit data on certain items which should
have been included. This will ultimately lead to fallacious conclusions.
(f)
Sources Of Information (Data):
After deciding about the unit, a researcher has to decide about the
source from which the information can be obtained or collected. For any
statistical inquiry, the investigator may collect the data first hand or he
may use the data from other published sources, such as publications of the
government/semi-government organizations or journals and magazines
etc.
(g)
Method Of Data Collection:
There is no problem if secondary data are used for research.
However, if primary data are to be collected, a decision has to be taken
whether (i) census method or (ii) sampling technique is to be used for
data collection. In census method, we go for total enumeration i.e., all
the units of a universe have to be investigated. But in sampling technique,
we inspect or study only a selected representative and adequate fraction
of the population and after analyzing the results of the sample data we
draw conclusions about the characteristics of the population. Selection
of a particular technique becomes difficult because where population
or census method is more scientific and 100% accuracy can be attained
through this method, choosing this becomes difficult because it is time
taking, it requires more labor and it is very expensive. Therefore, for a
single researcher or for a small institution it proves to be unsuitable. On
the other hand, sample method is less time taking, less laborious and less
expensive but a 100% accuracy cannot be attained through this method
because of sampling and non-sampling errors attached to this method.
Hence, a researcher has to be very cautious and careful while choosing a
particular method.
46
Methods of Collecting Primary Data:
Primary data may be obtained by applying any of the following
methods:
1. Direct Personal Interviews.
2. Indirect Oral Interviews.
3. Information from Correspondents.
4. Mailed Questionnaire Methods.
5. Schedule Sent Through Enumerators.
1.
Direct Personal Interviews:
A face to face contact is made with the informants (persons from
whom the information is to be obtained) under this method of collecting
data. The interviewer asks them questions pertaining to the survey and
collects the desired information. Thus, if a person wants to collect data
about the working conditions of the workers of the Tata Iron and Steel
Company, Jamshedpur, he would go to the factory, contact the workers
and obtain the desired information. The information collected in this
manner is first hand and also original in character. There are many merits
and demerits of this method, which are discussed as under:
Merits:
1. Most often respondents are happy to pass on the information required
from them when contacted personally and thus response is encouraging.
2. The information collected through this method is normally more
accurate because interviewer can clear doubts of the informants
about certain questions and thus obtain correct information. In case
the interviewer apprehends that the informant is not giving accurate
information, he may cross-examine him and thereby try to obtain the
information.
3. This method also provides the scope for getting supplementary
information from the informant, because while interviewing it is
possible to ask some supplementary questions which may be of greater
use later.
4. There might be some questions which the interviewer would find
difficult to ask directly, but with some tactfulness, he can mingle such
47
questions with others and get the desired information. He can twist
the questions keeping in mind the informant’s reaction. Precisely, a
delicate situation can usually he handled more effectively by a personal
interview than by other survey techniques.
5. The interviewer can adjust the language according to the status and
educational level of the person interviewed, and thereby can avoid
inconvenience and misinterpretation on the part of the informant.
Demerits:
1. This method can prove to be expensive if the number of informants is
large and the area is widely spread.
2. There is a greater chance of personal bias and prejudice under this
method as compared to other methods.
3. The interviewers have to be thoroughly trained and experienced;
otherwise they may not be able to obtain the desired information.
Untrained or poorly trained interviewers may spoil the entire work.
4. This method is more time taking as compared to others. This is because
interviews can be held only at the convenience of the informants.
Thus, if information is to be obtained from the working members
of households, interviews will have to be held in the evening or on
week end. Even during evening only an hour or two can be used for
interviews and hence, the work may have to be continued for a long
time, or a large number of people may have to be employed which may
involve huge expenses.
Conclusion:
Though there are some demerits in this method of data collection
still we cannot say that it is not useful. The matter of fact is that this
method is suitable for intensive rather than extensive field surveys. Hence,
it should be used only in those cases where intensive study of a limited
field is desired.
In the present time of extreme advancement in the communication
system, the investigator instead of going personally and conducting a face
to face interview may also obtain information over telephone. A good
number of surveys are being conducted every day by newspapers and
television channels by sending the reply either by e-mail or SMS. This
48
method has become very popular nowadays as it is less expensive and the
response is extremely quick. But this method suffers from some serious
defects, such as (a) those who own a phone or a television only can be
approached by this method, (b) only few questions can be asked over
phone or through television, (c) the respondents may give a vague and
reckless answers because answers on phone or through SMS would have
to be very short.
2.
Indirect Oral Interviews:
Under this method of data collection, the investigator contacts third
parties generally called ‘witnesses’ who are capable of supplying necessary
information. This method is generally adopted when the information
to be obtained is of a complex nature and informants are not inclined
to respond if approached directly. For example, when the researcher is
trying to obtain data on drug addiction or the habit of taking liquor, there
is high probability that the addicted person will not provide the desired
data and hence will disturb the whole research process. In this situation
taking the help of such persons or agencies or the neighbours who know
them well becomes necessary. Since these people know the person well,
they can provide the desired data. Enquiry Committees and Commissions
appointed by the Government generally adopt this method to get people’s
views and all possible details of the facts related to the enquiry.
Though this method is very popular, its correctness depends upon a
number of factors such as
1. The person or persons or agency whose help is solicited must be of
proven integrity; otherwise any bias or prejudice on their part will not
bring out the correct information and the whole process of research
will become useless.
2. The ability of the interviewers to draw information from witnesses by
means of appropriate questions and cross-examination.
3. It might happen that because of bribery, nepotism or certain other
reasons those who are collecting the information give it such a twist
that correct conclusions are not arrived at.
Therefore, for the success of this method it is necessary that the
evidence of one person alone is not relied upon. Views from other persons
49
and related agencies should also be ascertained to find the real position
.Utmost care must be exercised in the selection of these persons because it
is on their views that the final conclusions are reached.
3.
Information from Correspondents:
The investigator appoints local agents or correspondents in different
places to collect information under this method. These correspondents
collect and transmit the information to the central office where data are
processed. This method is generally adopted by news paper agencies.
Correspondents who are posted at different places supply information
relating to such events as accidents, riots, strikes, etc., to the head office.
The correspondents are generally paid staff or sometimes they may be
honorary correspondents also. This method is also adopted generally by
the government departments in such cases where regular information
is to be collected from a wide area. For example, in the construction of
a wholesale price index numbers regular information is obtained from
correspondents appointed in different areas. The biggest advantage of this
method is that, it is cheap and appropriate for extensive investigation. But
a word of caution is that it may not always ensure accurate results because
of the personal prejudice and bias of the correspondents. As stated earlier,
this method is suitable and adopted in those cases where the information
is to be obtained at regular intervals from a wide area.
4.
Mailed Questionnaire Method:
Under this method, a list of questions pertaining to the survey
which is known as ‘Questionnaire’ is prepared and sent to the various
informants by post. Sometimes the researcher himself too contacts the
respondents and gets the responses related to various questions in the
questionnaire. The questionnaire contains questions and provides space
for answers. A request is made to the informants through a covering letter
to fill up the questionnaire and send it back within a specified time. The
questionnaire studies can be classified on the basis of:
i. The degree to which the questionnaire is formalized or structured.
ii. The disguise or lack of disguise of the questionnaire and
iii. The communication method used.
50
When no formal questionnaire is used, interviewers adapt their
questioning to each interview as it progresses. They might even try to elicit
responses by indirect methods, such as showing pictures on which the
respondent comments. When a researcher follows a prescribed sequence
of questions, it is referred to as structured study. On the other hand, when