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Unformatted text preview: Stratified samples can produce sample statistics that are more precise (i.e.,
Stratification also allows the investigation of the characteristics of interest
for particular subgroups. 9. The difference between a proportionate stratified sample and a disproportionate
stratified sample: With a proportionate stratified sample, the number of observations
in the total sample is allocated among the subgroups, or strata, in proportion to the
relative number of elements in each stratum in the population. Disproportionate
stratified sampling involves balancing the two criteria of strata size and variability. 10. Steps in drawing a cluster sample.
The parent population is divided into mutually exclusive and exhaustive
A random sample of the subsets is selected and, generally, all elements of
those subsets are included in the sample. Sampling Steps
Defining the target population
A population is all cases that meet designated specifications for membership in the group
Researchers must be very clear and precise in defining the target population. Example: Households
in the city limits of Sacramento, California, with one or more children under the age of 18 living at
Identifying the sampling frame
A sampling frame is the list of population elements from which a sample will be drawn. Commonly
used sampling frames include: (a) Customer databases; (b) Telephone directories; (c) Lists
developed by data compilers.
Pick a sampling technique/procedure
Convenience Sample: Population elements are sampled because they are in the right place at the
right time. Sometimes referred to as “accidental” sampling. Easy to conduct, but there is no way to
know if sample is representative of the population (i.e., cannot statistically assess sampling error).
Examples include online or television “question of the day” polls
Judgment Sample: Population elements are handpicked because they are expected to serve the
research purpose. The researcher may believe that they are representative of the larger population or
that they can offer the information ne...
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- Fall '13