# Introduction

The idea of the **One factor At a Time** (OAT) {{doe}} is to observe the evolution of phenomena when 
one input factor is modified while all the others remain unchanged.

This {{doe}} can be used to compute partial derivatives or sensitivities. For the latter application, 
it is interesting as it provides a very simple and inexpensive way to evaluate the sensitivity of a 
phenomena to its input factors. However, it might not be the best solution as it does not explore 
multi-factorial and non-linear effects.