In this post I will derive a simple relationship between process shift and the capability indices Cp and Cpk.
An understanding of how variance propagates through a system can help us design experiments that maximise the precision of our results.
Traditionally scientists and engineers are taught how to conduct scientific experiments, then analyse the data in the context of their domain-specific knowledge (physics, chemistry, electronics, etc), and finally to apply statistical methods to calculate the precision of their results.
Statistical design of experiments reverses the sequence of data analysis, by first anticipating the precision of the results and how the precision is influenced by the experimental configuration. (more…)