Vormistamine ülesanne 3
Another form of
coverage error is overcoverage; here a unit from the target population appears more than once in the
sampling frame. Duplications like this can occur when a sampling frame results from the
combination of several lists. For example, on one list a woman is listed under her maiden name, and
on a second list under her married name. If these lists are combined, the same person is listed under
two different entries. Another example is surveys that use mobile (cell) telephones; these overcover
persons who own more than one phone. A third type of coverage error is caused by erroneous
inclusions in the frame. For example, a business number is included on a list with household phone
numbers.
As a final example, consider the case of web surveys. A common way to attract respondents to a
web survey is placing a link to the survey on a populaar web site. Basically, this means that the
researcher has no control over who responds to the questionnaire. Coverage error for web surveys is
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