However, you then have another problem called the placebo effect.

The most recent were designed to control for placebo effect.

We've come to understand that the placebo effect is real.

But there's a chance that something beyond the placebo effect is also at play.

The most direct impact on performance could be a placebo effect, he said.

A placebo effect may play a role in any intervention.

This study also noted a significant placebo effect in the control group.

"The placebo effect can be anywhere from 20 to 40 percent."

I can definitely say it was not a placebo effect.

"And sometimes this seems to help, though whether it's a placebo effect I'm never sure."