The document discusses sampling design, which involves selecting a portion of a population for making inferences about the whole. It covers the objectives, methods, and steps for determining sample size, as well as the characteristics of a good sample design to minimize errors. Additionally, the document addresses data collection methods and guidelines for designing effective questionnaires and conducting interviews.

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Sampling Design
Presented by
Dr. B. S. SAWANT
(M.Com(Stat.),M.C.M.,M.Phil,Ph.D.)
Director,
Rayat Shikshan Sanstha’s
Karmaveer Bhaurao Patil Institute of Management
Studies and Research,
Satara.

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Sampling Design
Sampling may be defined as the selection of same part of
aggregate or totality on the basis of which a judgments or
inference about the aggregate or totality is made. It is the process
of obtaining information about an entire population by examining
only a part of it.
Sampling theory is a study of relationships existing between a
population and sample drawn from the population. Sampling
theory is applicable only to random samples. The main problem of
sampling theory is the problem of relationship between parameter
and statistics .
Objective of Sampling theory:
•Statistical estimation : Unknown population
•Testing of hypothesis, Statistical inference

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Sample size & its determination:
• Nature of universe
• Number of classes proposed
• Nature of study
• Type of sampling
• Standard of accuracy & acceptance confidence level
• Availability of finance
• Other considerations-Nature of units, size of population, size of questionnaire,
availability of trained investigator
• Two approaches:
• To specify the precision of estimation desired & then to determine the sample size
necessary to insure it.
• Use Bayesian statistics to weight the cost of additional information against that expected
value of additional information.

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Need of samples:
• Sampling can save time and money
• Sampling may enable more accurate measurements for sample study
conducted by trained& experienced investigator
• Sample is used when population contains infinitely many members
• Sampling is only used when a test involves the destruction of the item
under study.
Criteria of selecting sampling procedure :
• Inappropriate sampling frame – biased
• Defective measuring devices , Non respondents
• Indeterminacy principle- Individual act differently when kept under
observation than what they do when kept in non-observed situations.
• Natural bias in reporting the data – sampling errors.

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Sampling Design
• All items in any field of enquiry constitute a Universe or population.
• A complete enumeration of all items in the population is known as a
census inquiry. This inquiry involves a great deal of time, money &
energy. When the field of inquiry is large, this method becomes
difficult to adopt because of the sources involved.
- Sample - The selected respondent
- Sampling technique - Selection process
- Sample survey - The survey so conducted
Implications of a sample design :
A sample design is a definite plan for obtaining a sample from a given
population. It refers to the technique or the procedure the researcher
would adopt. In selecting items for sample, the no. of items to be
involved in the sample i.e. the size of sample.
Sample design is determined before data are collected.

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Steps in sample design :
• Types of universe : Finite & Infinite
• Sampling unit: It may be a geographical one such as state, district, Village
• Source list: Sampling frame- It contains the name of all items of a universe
• Size of sample: It should be optimum & which is fulfills the requirements of efficiency,
representative ness, reliability& flexibility with budgetary constraints
• Sampling design: A sample design is a definite plan for obtaining a sample from
sampling frame.
• Statistics & Parameters – Statistic is a characteristic of a sample and parameter is a
characteristic of a population/
• Budgetary constraints – cost consideration
• Sampling procedure – type of sample
• Sampling errors: Inaccuracy is the information collected may be termed as sampling
errors . Sampling errors are those errors which arise on account of sampling.
Sampling error = frame error + chance error + response error

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Characteristics of a good sample design :
• Sample design must result in a truly representation of sample.
• Sample design must be such which results in a small sampling error.
• Sample design must be viable in the context of funds available for the
research study.
• Sample design must be such so that systematic bias can be controlled in a
better way.
• Sample design must be such that the results of the sample study can be
applied, in general, for the universe with a reasonable level of confidence.
Types of Sample designs:
Elements of selection Probability sampling Non probability Sampling
1. Unrestricted Sampling : S. R. S. Haphazard or
convenience
2. Restricted Sampling : Complex random Purposive sampling
such as Cluster, such as Quota,
Systematic, Stratified judgment etc.
etc.

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Methods of Data Collection :
• Selection of appropriate method for data collection
1. Nature, scope and object of enquiry 2. Availability of funds
3. Time factor 4. Precision required
Experimental or laboratory methods: Laboratory experiment, simulation, Field
experiments
• Non experimental methods:
a. Field Method- field study, sample survey, case study b. Laboratory method
Primary Data :
• Observation:
a. Simple or uncontrolled observation - Participation, non- participation & quast
observation , b. Systematic or controlled observation c. Mass observation
• Questionnaire- Degree of structure & no. of responses

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Guidelines for designing good questionnaire
- The questionnaire should be related to final objective of the investigation
- The questionnaire should be brief
- Questions outside the respondent’s experience should not be asked
- Past events, to much reliance should not be placed on the respondent’s memory
- Questions which are likely to grows bias in the respondent should be avoided.
- Questions should be clear and simple
- The structure of the question should be according to the form in which the
responses to recorded
- There should be logical sequence of questions in the questionnaire
- It is some times desirable to insert cross checks
- A mail questionnaire should always be accompanied by a letter
- If Questionnaire is to be translated for use into local respondent, the translated
version should be retranslated into original language to check its fidelity
- Every questionnaire should have an appropriate ending to it.
Format of the questionnaire
Title of organization
Pre testing
Advantages of pretesting,
Advantages/ Limitations of mail questionnaire

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Interview
• Types of Interview- Structured, unstructured, semi structure
• Process of Interview
- Preparatory thinking - developing rapport with respondent
- Carrying the interview forward – Recording the interview
- Closing the interview, Schedules, Others-
Warranty cards, Distributor audit,Pantry audit ,Consumer Panels
Mechanical devices- Bar code reader, eye camera,Pupil metric camera
Projective technique
Dept interview,Content analysis