What is Design of Experiments (DOE)?
Design of experiments is the statistical method for testing multiple factors simultaneously to find which ones (and which combinations) drive an outcome — instead of the slow one-factor-at-a-time approach that misses interactions entirely.
In projects it optimizes products and processes: fewer trials, more insight, and it's the only practical way to detect that factor A matters only when factor B is high.
Worked example
A concrete supplier wants a mix that cures faster without losing strength. Instead of 30 sequential trials, a DOE matrix varies cement type, admixture dose, and curing temperature across 8 runs — revealing the admixture only works at higher temperatures, an interaction one-at-a-time testing would have averaged away. The winning mix ships in two weeks.