Re: How many sample of MSA attribute?
The sample size depends on the process characteristics and the method. There are two pages on which the required sample size in an attribute measurement system study is mentioned in MSA 4th:
page 140-141 /risk analysis method (kappa coefficient):
Sample size should be established with respect to the process capability, the higher the capability, the more samples needed. In the example for a capability of Pp=Ppk=0.5 (corresponding to a 13% nonconformance rate) the sample size was set to n=50.
page 145 / analytical method:
"Eight parts should be selected at as nearly equidistant intervals as practical.[...] The eight parts must be run through the gage, m=20 times, and the number of accepts ,(a), recorded."
Hope this helps,
Barbara