Though sampling is not new, the sampling theory has been developed recently.
Though sampling is not new, the
sampling theory has been developed recently. People knew or not but they have
been using the sampling technique in their day to day life. For example a house
wife tests a small quantity of rice to see whether it has been well-cooked and
gives the generalized result about the whole rice boiling in the vessel. The
result arrived at is most of the times 100% correct. In another example, when a
doctor wants to examine the blood for any deficiency, takes only a few drops of
blood of the patient and examines. The result arrived at is most of the times
correct and represent the whole amount of blood available in the body of the
patient. In all these cases, by inspecting a few, they simply believe that the
samples give a correct idea about the population. Most of our decision are
based on the examination of a few items only i.e. Sample studies.
In the words of Croxton and Cowdon, “It may be too expensive or too time consuming to attempt either a complete
or a nearly complete coverage in a statistical study. Further to arrive at
valid conclusions, it may not be necessary to enumerate all or nearly all of a
population. We may study a sample drawn from the large population and if that
sample is adequately representative of the population, we should be able to
arrive at valid conclusions.”
According to Rosander, “The
sample has many advantages over a census or complete enumeration. If carefully
designed, the sample is not only considerably cheaper but may give results which
are just accurate and sometimes more accurate than those of a census. Hence a
carefully designed sample may actually be better than a poorly planned and
1. It saves time:
Sampling method of data
collection saves time because fewer items are collected and processed. When the
results are urgently required, this method is very helpful.
2. It reduces cost:
Since only a few and selected
items are studied in sampling, there is reduction in cost of money and
reduction in terms of man hours.
3. More reliable results can be obtained:
sampling, more reliable results can be obtained because there are fewer chances of sampling statistical errors. If there is
sampling error, it is possible to estimate and control the results.(b) Highly
experienced and trained persons can be employed for scientific processing and
analyzing of relatively limited data and they can use their high technical
knowledge and get more accurate and reliable results.
4. It provides more detailed information:
As it saves time, money and labor, more detail information can be
collected in a sample survey.
only sampling method to depend upon:
Some times it so happens that one
has to depend upon sampling method alone because if the population under study
is finite, sampling method is the only method to be used. For example, if
someone’s blood has to be examined, it will become fatal to take all the blood
out from the body and study depending upon the total enumeration method.
6. Administrative convenience:
The organization and
administration of sample survey are easy for the reasons which have been
7. More scientific:
Since the methods used to collect
data are based on scientific theory and results obtained can be tested,
sampling is a more scientific method of collecting data.
It is not that sampling is free from demerits or
shortcomings. There are certain shortcomings of this method which are discussed below:
Illusory conclusion: If a sample enquiry is not carefully planned and executed, the
conclusions may be inaccurate and misleading.
Sample Not Representative: To make the sample representative
is a difficult task. If a representative sample is taken from the universe, the
result is applicable to the whole population. If the sample is not
representative of the universe the result may be false and misleading.
Lack Of Experts: As there are lack of experts to plan and conduct a sample survey, its
execution and analysis, and its results would be Unsatisfactory and not
Sometimes More Difficult Than Census Method: Sometimes the sampling plan may be complicated and requires more money,
labor and time than a census method.
Personal Bias: There may be personal biases and prejudices with regard to the choice of
technique and drawing of sampling units.
Choice Of Sample Size: If the size of the sample is not appropriate then it may lead to untrue
characteristics of the population.
Conditions Of Complete Coverage: If the information is required for each and every item of the universe,
then a complete enumeration survey is better.
of sampling: In order to reach a clear conclusion, the sampling should possess the
1. It must be representative: The sample selected should possess the similar characteristics of the
original universe from which it has been drawn.
Selected samples from the universe should have similar nature and should
mot have any difference when compared with the universe.
In order to have a more reliable and representative result, a good
number of items are to be included in the sample.
All efforts should be made to get
maximum results both in terms of cost as well as efficiency. If the size of the
sample is larger, there is better efficiency and at the same time the cost is
more. A proper size of sample is maintained in order to have optimized results
in terms of cost and efficiency.
Tags : Research Methodology - Questionnaire & Sampling
Last 30 days 960 views