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What is a Sample Survey?

A sample survey is a research method used to collect data from a subset or sample of individuals or units within a larger population. The purpose of a sample survey is to gather information about the characteristics, attitudes, behaviors, or opinions of the population, which can then be generalized to the entire population.

Sample surveys are commonly used in various fields, including social sciences, market research, public opinion polling, and epidemiology, to obtain insights, make inferences, and inform decision-making based on representative samples of the population.

Steps in a Sample Survey

The following are the steps in a sample survey:

1. Define Target Population
2. Select Sampling Scheme and Sample Size
3. Develop Questionnaire
4. Recruit and Train Field Investigators
5. Obtain Information as Per Questionnaire
6. Scrutinize Information Gathered
7. Analyze and Interpret Information

Define Target Population

In defining the target population the important terms should be carefully and unambiguously defined. The target population may be divided into various segments which may have differing characteristics. For example, all television owners may be divided into three to four income brackets.

Select Sampling Scheme and Sample Size

There are several sampling schemes: simple random sampling, cluster sampling, sequential sampling, stratified sampling, systematic sampling, and non-probability sampling. Each scheme has its advantages and limitations. The sample size has a bearing on the reliability of the estimates-the larger the sample size, the greater the reliability.

Develop Questionnaire

The questionnaire is the principal instrument for eliciting information from the sample of the respondents. The effectiveness of the questionnaire as a device for eliciting the desired information depends on its length, the types of questions, and the wording of questions.

Developing the questionnaire requires a thorough understanding of the product/service and its usage, imagination, insights into human behavior, and familiarity with the tools of descriptive and inferential statistics to be used later for analysis. It also requires knowledge of psychological scaling techniques if the same are employed for obtaining information relating to attitudes, motivations, and psychological traits.

Industry and trade market surveys, in comparison to consumer surveys, generally involve more technical and specialized questions. Since the quality of the questionnaire has an important bearing on the results of the market survey, the questionnaire should be tried out in a pilot survey and modified in the light of problems/difficulties noted.

Recruit and Train Field Investigators

Recruiting and training of field investigators must be planned well. Great care must be taken in recruiting the right kind of investigators and imparting the proper kind of training to them.

Investigators involved in industry and trade market surveys need intimate knowledge of the product and technical background, particularly for products based on sophisticated technologies.

Obtain Information as Per Questionnaire

Respondents may be interviewed personally, telephonically, or by mail for obtaining information. Personal interviews ensure a high rate of response. They are, however, expensive and likely to result in biased responses because of the presence of the interviewer.

Mail surveys are economical and evoke fairly candid responses. The response rate, however, is often low. Telephonic interviews, common in Western countries, have very limited applicability in India because telephone tariffs are high and telephone connections are few.

Scrutinize Information Gathered

Information gathered should be thoroughly scrutinized to eliminate data that is inconsistent and of dubious validity.

For example, a respondent with a high income and a large family may say that he lives in a one-room house. Such information, probably inaccurate, should be deleted. Sometimes data inconsistencies may be revealed only after some analysis.

Analyze and Interpret Information

Information gathered in the survey needs to be analyzed and interpreted with care and imagination. After tabulating it as per a plan of analysis, suitable statistical investigation may be conducted, wherever possible and necessary.

For purposes of statistical analysis, a variety of methods are available. They may be divided into two broad categories: parametric methods and non-parametric methods. Parametric methods assume that the variable or attribute under study conforms to some known distribution. Non-parametric methods do not presuppose any particular distribution.

The results of data based on the sample survey will have to be extrapolated to the target population. For this purpose, appropriate inflationary factors, based on the ratio of the size of the target population to the size of the sample studied, will have to be used. The statistical analysis of data should be directed by a person who has a good background in statistics as well as economics.

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