The experiment using signal factor is the sampling for the data of stratified Regression Analysis . So this experiment can be the experiment of natural laws and principles.
Quality engineering tells us the importance of such experiment to control quality of products.
In addition to the experiment above, there are applications of signal factors.
Linearity is important for measuring method. If we cannot confirm the linearity of measuring method, we cannot proofread the measuring instruments.
The signal factor is the difference of samples in the study of measuring method.
For the experiment of time dependent phenomena, we define time as the signal factor. The output of this experiment can be used as the data of Time Series Analysis .