How to Validate your Decisions Using Statistics (Analysis of Variance) – Part I

Are we producing the desired effects?In manufacturing environments, as well as in many other settings, we take actions and modify parameters, procedures and processes to obtain a specific result (usually to improve the situation). In these cases we need to know if the obtained result is a expected consequence of our changes or we’re just observing variations inherent to the population, that are not related to our actions.

One of the techniques we can use is the Analysis of Variance which is a powerful tool used in statistical design of experiments, Lean Manufacturing, Reliability Engineering and in situations involving many variables and/or samples from different populations.

It’s true that many software can perform this calculation automatically; however, it’s important to know how the method works – at least with a simple example like the one below – to be able to interpret and take advantage of the results the software we’ll give us when solving more complex problems. Continue reading