To determine appropriate sample size, it is necessary to consider the maximum sample error we are willing to accept, as well as the confidence level desired. Different research requires different degrees of reliability or "precision", depending on the specific objectives and possible consequences of the survey findings.
Often, an "acceptable" level of error used by survey researchers is between 5% and 10% at the 95% confidence level.
Another factor in determining sample size is the number of subgroups to be analyzed. A researcher will want to be sure that the smallest subgroup will be large enough to insure reliable results.
The sample precision analysis can provide data to help a researcher make an informed decision regarding sample reliability.
NOTICE Documentation and original code copyright 1995-2006 by DataStar, Inc. (Waltham, MA). Reproduction of material for non-commercial purposes is permitted, without charge, provided that suitable reference is made to Starware/Stat and DataStar, Inc.
Neither Starware/Stat nor its documentation should be modified in any way without written permission from DataStar, Inc.
DISCLAIMER Starware/Stat is provided "as is" without warranty of any kind. The entire risk as to the quality, performance, and fitness for intended purpose is with you. You assume responsibility for the selection of the test and for the use of results obtained.
More information on Z-Tests
More information on T-Tests
More information on Sample Precision
NOTICE
Documentation and original code copyright 1995-2006 by DataStar, Inc. (Waltham, MA). Reproduction of material for non-commercial purposes is permitted, without charge, provided that suitable reference is made to Starware/Stat and DataStar, Inc.
Neither Starware/Stat nor its documentation should be modified in any way without written permission from DataStar, Inc.
DISCLAIMER
Starware/Stat is provided "as is" without warranty of any kind. The entire risk as to the quality, performance, and fitness for intended purpose is with you. You assume responsibility for the selection of the test and for the use of results obtained.
References
DataStar, Inc.
85 River Street, Waltham, MA 02453
781-647-7900
www.surveystar.com