Business Research Methods Types of Sampling

Sampling Methods/ Designs Types of Sampling Probability Sampling Methods Simple Stratified Cluster Multi-stage Non-Probability Sampling Methods Convenience Judge ment Quota Snowball

Probability Sampling Method Sample units selected at Random Equal chance for being selected as representative Provide unbiased information Independent and Impartial selection of Sample Based on the theory of Probability

1.A. Simple Random Sampling Selection of sample at random Useful for telephone/ mail survey Methods: Lottery Sampling (no. selected between 1 & 10) e.g. 3,13,23,33,43,53 and so on Sampling by the use of random number tables Arranged numerically for selection

1. B. Stratified Sampling Proportional Random Sampling Population> Groups> Sample Basis of Group Formations Geographical Area Size of Household Income An improvement over simple random sampling because the group is tried to be made more representative E.g All Students>Year>Sample

1. C. Cluster Sampling Group wise inclusion in the sample Individual units are clubbed together E.g. Total universe > Groups In this case , the sample under study is a group selected out of the universe Savings in costs & time Greater danger of over/ under representation

1.D. Multi- Stage Sampling Sampling is done at multiple stages Applicable in big enquiries extending to a large geographical area , say, the whole country E.g. Working efficiency of nationalized banks India > State wise > District wise Flexible Time & Effort Large number in a given cost Surveys of underdeveloped areas of a country

Non-Probability Sampling Purposive selection Based on convenience & judgement of researcher Subjective, by the researcher himself Sample selected may not be the representative of the entire universe Less cost, less time, Little statistical application

2.A. Convenience Sampling Importance to the convenience of Researcher Easily accessible, readily available, easily measurable samples are selected Accidental Sampling Likely to be biased Examples – Interviewing respondents at public places Advantages Disadvantages Pretesting Non representative Tension free researcher No equal chance Convenience to Researcher Cannot rule out bias of respondents

2.B. Judgement Sampling Purposive Selection of sample as per the expert judgement of the researcher Expert in the subject of research must be selected E.g. To study the effect of promotion activities, a marketing expert may be appointed for sampling purpose & further research

2.C. Quota Sampling Universe > Identical Groups > Sample Size of the sample , decided by the researcher Investigators are given full freedom to select sample from the given quota of sample items Selection is as per their convenience Quick & easy Economical Errors , due to preferences & prejudices of the researcher

2.D. Snowball Sampling Sample selected and asked to select the further sample One respondent being used to generate the names of others is snowball sampling Networking for finding out respondents of some rare type Small pool of initial infromants> Social Networks > Eligibility criteria > Contribute Advantages Disadvantages Low Cost Community Bias Locate hidden population Vague sample size Locate people of a specific population Little Control

Distinction – Probability v/s Non-Probability Sampling Equal Chance Systematic & Modern Controlled Objectively Mechanical & Mathemetical Process Selection by chance Probability Sampling No equal opportunity Traditional, outdated Subjective Mental Process Selection by choice Non Probability Sampling

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