I am currently working for a project team that is trying to reduce the number of defective parts produced in a factory.
Without going into too much detail, the plant has a safety procedure where they check a sample of parts for a fault. They calculate their efficiency via the formula $\frac{\text{NON Faulty Parts}}{\text{Total Parts Processed}}$.
Recently we have had an upsurge in the number of parts processed and the performance has dropped by 2%, even though our goal was to increase it.
I want a statistical test that will tell us if our project has been successful and whether the decrease in performance can be ascribed to a larger number of analysed parts.
Can anyone point me in the right direction as to the sort of test I could use using R
?