Choose the right word
effective, effectual, efficacious, efficient
All of these adjectives mean producing or capable of producing a result, but they are not interchangeable. Use effective when you want to describe something that produces a definite effect or result ( an effective speaker who was able to rally the crowd's support) and efficacious when it produces the desired effect or result ( an efficacious remedy that cured her almost immediately). If something produces the desired effect or result in a decisive manner, use effectual ( an effectual recommendation that got him the job), an adjective that is often employed when looking back after an event is over ( an effectual strategy that finally turned the tide in their favor). Reserve the use of efficient for when you want to imply skill and economy of energy in producing the desired result ( so efficient in her management of the company that layoffs were not necessary). When applied to people, efficient means capable or competent ( an efficient homemaker) and places less emphasis on the achievement of results and more on the skills involved.