efficacy

"There's a pipeline where you've got to prove safety and then prove efficacy, and you've got to do that right," he said.

But even if it passes off smoothly and gaffe-free questions may remain about its efficacy.

The efficacy of Deen’s waterworks will depend on how much the viewer is willing to buy.

An activist group he ran for eight years, Children's Health Defense, repeatedly questioned the safety and efficacy of vaccination.

She felt that they took no real accountability for the pitfalls of their product, and was let down by their decision to continue selling it for two months despite doubts over its efficacy.