Words / C1

EF-ik-uh-see/ˈefɪkəsi/

Efficacy is the ability of a treatment, policy, or method to produce the intended result: clinical efficacy, efficacy of a scheme. Effectiveness is the close twin, often in real-world use; efficiency is less waste; a testimonial is not an n. Formal papers prefer efficacy for interventions.

Meaning

The ability of something to produce the result it is meant to produce.

Examples

• “Efficacy of the intervention is an n with a control, not a testimonial reel.”
• “Effectiveness is the close twin. Efficiency is cost/waste. A reel is comms. A control and a count are methods. Show the n; keep the thanks for the acknowledgements.”

Good to know

How well it actually works. Close: effectiveness. Contrast: efficiency (less waste); a testimonial. Needs an n and usually a control.

Near in meaning

effectiveness

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