# Acceptable maximum RSD (relative standard deviation) for an sample size

#### v9991

Trusted Information Resource
for verifying suitability of equipment before using to analyse an sample,
we measure the response of sample for 6 times ( n=6), and verify the %RSD.

1) This query is about how to determine statistical criteria for maximum %RSD (relative standard deviation) for a given sample size ;

2) Following is one such reference...
%RSD = KBsq( n) /t(90%,n−1)
B = specification window ( upper - target)
n = sample size
t = Student’s t at the 90% probability level (double sided) with n−1 degrees of freedom.

i couldn't interpret / infer "k"

3. can i use the Minitab option for stat > acceptance sampling by variables ; and even here any guidance on setting the variables of AOQL, k value,

Last edited:

#### v9991

Trusted Information Resource
for verifying suitability of equipment before using to analyse an sample,
we measure the response of sample for 6 times ( n=6), and verify the %RSD.

2) Following is one such reference...
%RSD = KBsq( n) /t(90%,n−1)
B = specification window ( upper - target)
n = sample size
t = Student’s t at the 90% probability level (double sided) with n−1 degrees of freedom.
Here's is one attempt to emulate above formula. ( considering
k2, two sided tolerance interval)
and B is considered as method-precision target, repeatability)
Blue color cells are interim-calculations of formula-constituent. and green color cell is final % RSD value

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