Have you ever heard of the control charts?
Control charts are two-dimensional charts, where the vertical axis represents the value of the variable of interest. On this axis, there are three lines, the center line (CL) and the upper limits (UCL, upper control limit) and lower (CLC, lower control limit).
The center line represents some measure of centralization of the data, for example the mean. The upper and lower limits represent some measure of dispersion of the data, such as the distance between the mean and three standard deviations.
What we do by controlling the processes by means of control charts is a continuous hypothesis test to check if the process is under control.
When is a process under control? It is when the observed variation is natural and attributed to random, both the mean and the standard deviation of the sample being within the natural limits.
Example of a CUSUM control chart:
In the end, what we have to stick with are two main ideas: We need to know, understand, and interpret our data correctly to make decisions, correct errors and increase our productivity and profitability.
A last thought:
What is not defined cannot be measured. What is not measured cannot improve. What is not improved, is always degraded. Lod Kelvin
At Tests&Trials, we lead this type of projects to help our customers to continuously improve in their processes and never be a step back. But, if you prefer to maintain things internally, our statistical application Síagro is developed in a way that to can easily and in real time carry out this statistical analysis. You only need to contact us and get your password to start improving.