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MULTISTAGE, PURPOSIVE, SNOWBALL SAMPLING

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SREEDRISYA V

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MULTISTAGE SAMPLING

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  • Under this method, sample is prepared by stages. This population is divided into a number of large sampling units, each of which in turns is divided into smaller units, and so on.

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  • Suppose we want to take a sample of 5000 households from Kerala.

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  • At the first stage, the state may be divided into a number of district and a few district selected at random.

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  • At the second stage, each district may be divided into a number of villages and a sample of villages may be taken at random.

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At the third stage, 5000 households may be selected from the villages selected at the second stage.

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  • Multistage sampling is a complex form of cluster sampling. We use variety of Sampling methods together.

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  • Sampling scheme that combine several methods are called Multistage samples.

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ADVANTAGES

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  • Cost and speed that the survey can be done in less.

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  • Convenience of finding the survey sample.

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  • Normally more accurate than cluster sampling for the same size sample.

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DISADVANTAGES

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  • Not as accurate as simple random sample if the sample is the same size.

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  • More testing is more difficult

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PURPOSIVE SAMPLING

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  • This method means delibrate selection of sample units that conform to some predetermined criteria.

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  • This involves selection of cases which we judge as the most appropriate ones for the given study. It is based on the judgement of the researcher or some experts.

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  • This sampling method is also known as judgemental sampling.

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ADVANTAGES

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  • Simple to draw sample and useful in explorative studies.

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  • Save resources, as it requires less field work.

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DISADVANTAGES

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  • Require considerable knowledge about the population

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  • It is not always reliable sample, as conscious bias may exist.

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SNOWBALL SAMPLING

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  • Snowball sampling is a type of non- probability sampling technique

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  • Snowball Sampling is choosing the participants to find more participants for making a Sample group.

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  • Mostly researchers used this sample technique where participants are difficult to locate in a general population.

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  • Snowball sampling technique works as a changing system.

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  • There are two important things to remember in snowball sampling.

1. To find one or more research participant for research.

2. To take reference of participant to get more sample size in

research.

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ADVANTAGES

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  • Low cost.

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  • Useful in specific circumstances and for locating rare population.

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DISADVANTAGES

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  • Not independent.

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  • Projecting data beyond sample not justified.

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THANKYOU