Business Research Methods Types of Sampling Sampling Methods
Business Research Methods Types of Sampling
Sampling Methods/ Designs Types of Sampling Non-Probability Sampling Methods Simple Stratified Cluster Mult istage 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 theory of Probability
1. A. Simple Random Sampling Ø Selection of sample at random Ø Useful for telephone/ mail survey Ø Methods: Lottery Sampling (no. selected between 1 & 10) e. g. 3, 13, 23, 33, 43, 53 and so on o Sampling by the use of random number tables Arranged numerically for selection o
1. B. Stratified Sampling Ø Proportional Random Sampling Ø Population> Groups> Sample Ø Basis of Group Formations a. Geographical Area b. Size of Household c. Income Ø An improvement over simple random sampling because the group is tried to be made more representative Ø E. g All Students>Year>Sample
1. C. Cluster Sampling Ø Group wise inclusion in the sample Ø Individual units are clubbed together Ø E. g. Total universe > Groups In this case , the sample under study is a group selected out of the universe Ø Savings in costs & time Ø 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 Ø Purposive selection Ø Based on convenience & judgement of researcher Ø Subjective, by the researcher himself Ø Sample selected may not be the representative of the entire universe Ø 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 Non Probability Sampling Mental Process Equal Chance No equal opportunity Systematic & Modern Controlled Objectively Mechanical & Mathemetical Process Selection by chance Traditional, outdated Selection by choice Subjective
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