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confidence level/ sample size
Message posted by Sarah Siegfried (via 192.216.61.102) on February 22, 2001 at 9:48 AM (ET)
I have a total of 22,000 items.
I need to know what the sample size
needs to be to get 95%, 90%, 85%, 80%
confidence levels.
READERS RESPOND:
(In chronological order. Most recent at the bottom.)
Re: confidence level/ sample size
Message posted by Bill (via 192.231.71.108) on February 23, 2001 at 3:03 PM (ET)
I assume that the 22k is the population size although the population size does not matter. The simple answer is that n=z squared / 4 * (acceptable error)squared. For the 95% confidence interval n=1.96 squared/4 * (.95) squared or about 400, where z is the z value associated with the level of confidence, .95 in this case. A more precise and correct answer would include many caveats concerning the number and type of variables in the survey, the sample size of subgroups in the population, etc.
Re: confidence level/ sample size
Message posted by Sarah (via 192.216.61.102) on February 23, 2001 at 3:51 PM (ET)
Thank you for your response. It came just in time to end my work week on a positive note.
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