In the planner's view, Rumsfeld had two goals: to demonstrate the efficacy of precision bombing and to "do the war on the cheap."—Seymour M. Hersh, New Yorker, 7 Apr. 2003Vaccines exist, but their efficacy against aerosolized plague is unknown.—Sharon Begley et al., Newsweek, 8 Oct. 2001… efficacy does not have to be demonstrated before homeopathic products are marketed.—Alison Abbott et al., Nature, 26 Sept. 1996
questioned the efficacy of the alarms in actually preventing auto theft
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What's particularly interesting is how the human variable plays a role: AI’s efficacy changes based on whom it's being compared to.—Andrew Allen, Forbes, 24 Feb. 2025 Beyond mascara, Howard suggests looking out for skin-loving ingredients to help boost the texture and efficacy of products.—Conçetta Ciarlo, Vogue, 24 Feb. 2025 Then her oncologists will repeat an MRI to check on the egg-like masses on her liver to measure the treatment's efficacy.—Staff Author, People.com, 21 Feb. 2025 One of the possible reasons for the disconnect between the use of injections for back pain and their actual efficacy might be confirmation bias.—Michael Franco, New Atlas, 20 Feb. 2025 See All Example Sentences for efficacy
Word History
Etymology
borrowed from Latin efficācia, from efficāc-, efficāx "capable of fulfilling a function, efficacious" + -ia-y entry 2
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