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Five types of sampling zRandom (or simple random) zStratified random zCluster sampling zSystematic zArea probability.

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Presentation on theme: "Five types of sampling zRandom (or simple random) zStratified random zCluster sampling zSystematic zArea probability."— Presentation transcript:

1 Five types of sampling zRandom (or simple random) zStratified random zCluster sampling zSystematic zArea probability

2 Random zEvery subject is known zEvery subject has equal or know probability of selection

3 Random zAdvantages: yDon’t have to know the characteristics of a population yTends to be completely representative zDisadvantages: yComplete list is difficult to obtain yAlways a chance of drawing a misleading sample yNeeds a larger sample size

4 Stratified random zPopulation classified into two or more strata zSample drawn from each one zCases drawn in proportion to representation in population zCases can be oversampled, if needed

5 Stratified random zAdvantages: yCan be sure no relevant group is omitted yGreater precision possible with lower sample size zDisadvantages: yNeed to know about the population yProportions must be known yDifficulty in locating cases

6 Systematic random zSelection of every nth name zUsually quicker

7 Cluster zDone for efficiency zPopulation is broken down into smaller groups zUseful when no sampling frame is available

8 Area zCombines cluster and systematic zBased on geography


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