Sampling Sampling

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    SAMPLINGSAMPLINGSAMPLINGSAMPLING

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    Definition Sampling is the process of selecting a

    small number of elements from a

    larger defined target group ofelements such that the informationgathered from the small group will

    allow judgments to be made aboutthe larger groups

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    Terms used in sampling

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    METHODS OF SAMPLING

    Probability

    sampling

    Nonprobabilitysampling

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    Nonprobability Convenience

    sampling Judgment sampling Quota sampling Snowball sampling

    Probability Simple random

    sampling Systematic random

    sampling Stratified random

    sampling Cluster sampling

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    Probability samples:ones in which

    members of the population have aknown chance (probability) of beingselected

    Non-probability samples:instancesin which the chances (probability) ofselecting members from thepopulation are unknown

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    SIMPLE RANDOM

    SAMPLING

    Simple random sampling: theprobability of being selected is

    known and equal for all membersof the population

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    SYSTEMATIC RANDOM

    SAMPLING It is a method of probability sampling in which thedefined target population is ordered and thesample is selected according to position using askip interval.

    Sample is chosen by se3lecting a random startingpoint and then picking every ith element insuccession from the sampling frame .

    Ith= sampling interval

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    1: Obtain a list of units that contains anacceptable frame of the target population

    2: Determine the number of units in the list andthe desired sample size

    3: Compute the skip interval 4: Determine a random start point 5: Beginning at the start point, select the units

    by choosing each unit that corresponds to theskip interval

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    STRATIFIED RANDOM

    SAMPLING It is a method of probability samplingin which the population is divided into

    different sub groups and samples areselected from each.

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    1: Divide the target population intohomogeneous subgroups or strata

    2: Draw random samples fro each stratum

    3: Combine the samples from eachstratum into a single sample of the targetpopulation

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    CLUSTER SAMPLINGCLUSTER SAMPLING

    Cluster sampling involves growing theelements in a population into various

    clusters and then selecting a fewclusters randomly for further study.

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    The researcher should ensure

    that clusters are homogeneous(based on some characteristic ofthe units ) in nature and the

    elements in the cluster are asheterogeneous as possible i.e.each cluster should be similar tothe population.

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    Convenience sampling relies

    upon convenience and access

    Judgment sampling relies upon belief

    that participants fit characteristics

    Quota sampling emphasizes representation

    of specific characteristics

    Snowball sampling relies upon respondent

    referrals of others with like characteristics

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    Convenience sampling samples are selected based onconvenience

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    judgmental sampling In judgmental sampling, the persondoing the sample uses his/her

    knowledge or experience to selectthe items to be sampled.