Research Methodology - Questionnaire & Sampling
SAMPLING
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Though sampling is not new, the sampling theory has been developed recently.
SAMPLING
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 executed census.”
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.
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.
Through 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.
As it saves time, money and labor, more detail information can be collected in a sample survey.
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.
The organization and administration of sample survey are easy for the reasons which have been discussed earlier.
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:
If a sample enquiry is not carefully planned and executed, the conclusions may be inaccurate and misleading.
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.
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 trustworthy.
Sometimes the sampling plan may be complicated and requires more money, labor and time than a census method.
There may be personal biases and prejudices with regard to the choice of technique and drawing of sampling units.
If the size of the sample is not appropriate then it may lead to untrue characteristics of the population.
If the information is required for each and every item of the universe, then a complete enumeration survey is better.
In order to reach a clear conclusion, the sampling should possess the following essentials:
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.
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 executed census.”
Merits:
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:
Through 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.
5. Sometimes 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 discussed earlier.
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.
Demerits
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 trustworthy.
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.
Essentials of sampling:
In order to reach a clear conclusion, the sampling should possess the following essentials:
1. It must be representative:
The sample selected should possess the similar characteristics of the original universe from which it has been drawn.
2. Homogeneity:
Selected samples from the universe should have similar nature and should mot have any difference when compared with the universe.
3. Adequate samples:
In order to have a more reliable and representative result, a good number of items are to be included in the sample.
4. Optimization:
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
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