efficacy
power to produce a result
Roots
- e- / ex-: out, out of, away, or forth
- fac / fic / fact: do or make
Other words with the fac / fic / fact root
- affectation: an artificial display meant to impress
- artificial: made by humans; not natural
- benefactor: person who gives help, money, or support
- beneficent: doing good or producing benefit
- beneficial: helpful or producing good effects
- certify: to confirm officially as true
- effect: a result or outcome
- efficacious: effective; producing the intended result
Efficacy is effect-making power: the thing can actually do what it claims.
The study tested the efficacy of the new tutoring method.