Sample Size

All posts tagged Sample Size

This website has some easy to understand information on sampling tables:

http://www.sofeast.com/aql-tables/

The first table gives us the code for the sample size based on our lot/batch size:

Sample size code

For thie table if we’re dealing with general inspection levels we can choose between:

a. Reduced (General inspection level 1)

b. Normal (General inspection level 2)

c. Tightened (General inspection level 3)

Once we have a code for our choice of inspection level we can then move to the second table to determine our sample size.

Sample size table

If for example our lot size is 1000 and our inspection level has been decided as level 2 (normal) then our code letter is “J”. This indicates a sample size for this lot as 80. If we have decided that our AQL (Acceptance Quality Level) level is 1 then we will accept the lot/batch if we have less then or equal to 2 rejects in the 80 sampled. If we have 3 rejects in the 80 sampled then we reject the lot/batch.

This is a really nice and easy paper to read that explains why we need statistics and data records not only in the scientific world but also in the pharmaceutical and medical device industry.

Twenty tips for interpreting scientific claims

science-20-rules-01

Image Courtesy: http://mkweb.bcgsc.ca/