The '''one-factor-at-a-time method''' (or OFAT) is a method of [[design of experiments|designing experiments]] involving the testing of [[factor]]sfactors, or causes, one at a time instead of all simultaneously. Prominent text books and academic papers currently favor [[factorial design|factorial experimental designs]], a method pioneered by [[Ronald Fisher|Sir Ronald A. Fisher]], where multiple factors are changed at once. The reasons stated for favoring the use of factorial design over OFAT are:
1. OFAT requires more runs for the same precision in effect estimation<br />
