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10 Cards in this Set
- Front
- Back
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Sampling |
Researchersfrequently draw a sample from a population. -Sample = Statistics
Thesample key is for -Representing the population -Making inferences to the largerpopulation
KeyConcepts -SamplingFrame (target population) -SamplingRatio -SamplingError |
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Types of Sampling |
Twomain types of sampling:
Probability •SimpleRandom •Systematic •Stratified •Cluster •RandomDigit Dialing Non-probability •Convenience •Quota |
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Probability Sampling |
sampling method that relies on a random, or chance, selection method so that the probability of selection of population elements is known 1. Simple Random 2. Systematic Sampling 3. Stratified Sampling 4. Cluster Sampling 5. Random Digit Dialing |
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Simple Random |
every sample element is selected purely on the basis of chance through a random process. easiest model of random sampling no guarantee that sample perfectly represents that population |
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Systematic Sampling |
sample elements are selected from a list or from sequential files, with every nth element being selected after the first element is selected randomly do not use if elements within a sample are patterned |
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Stratified Sampling |
sample elements are selected separately from population strata that the researcher identifies in advance -divide the population into sub populations -draws a random sample from each sub population |
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Cluster Sampling |
elements are selected in two or more stages, with the first stage being the random selection of naturally occurring clusters and the last stage being the random selection of elements within the cluster -used to cover large geographic areas -less costly but less accurate |
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Random Digit Dialing |
The random dialing, by machine, of numbers within designated phone prefixes, which creates a random sample for phone surveys. -Usedwhen conducting telephone research -Avoidsproblem of telephone directories -Problematic– phone number belongs to more than one individual |
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Non-Probability Sampling |
-non random selection procedure -greater sampling errors
1. Convenience/haphazard -cheap and quick -systematic errors 2. Quota -identifies relevant categories (gender, age range) -number of people in each category is set -improvement over haphazard but not ideal |
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Sample Size |
-usually want as large as possible - more statistical power and ability to generalize results Considerations: -If conducting a pilot study – usea smaller sample -If documenting the incidence ofsomething rare – need a very large sample -If there is little variability intarget population on variable of interest - can use a smaller sample -Iflooking for small differences need a large sample |
