Estimation standard deviation duplicate or triplicate analysis when standard deviation for X measurements is known

Posted by John den Dunnen on Feb 20, 2007; 7:05pm
URL: http://spssx-discussion.165.s1.nabble.com/Problem-with-ANOVA-tp1073925p1073927.html

Hello,

I send this off topic question a view days ago to the list. Some people
asked for clarrification, therefore I rephrased my question. Who can help me
with my off topic question.

A sample was analyzed x (for e.g., 15)  times. I used the descriptive
funtion to calculate the mean and standard deviation (square root of the
average of the squares of deviations about the mean of a set of data) of
these measurements.

This sample will be used as In Process Control for the assay. For this
purpose the sample will be analyzed in duplicate or triplicate.

I want to set a criteria for the standard deviation of this duplicate or
triplicate analysis. These criteria should be based on the standarddeviation
of the x (for e.g., 15) measurements.

How can I estimate the standard deviation for tese duplicate and triplicate
measurements.

With regards,

John