He put forward a plan for improving office efficiency.

Can you guess which cooler is the most efficient?

This computer is powerful, efficient, and easy to use.

I hear that studying in the morning is more effective. Studying one hour in the morning is as good as three hours at night.

This behavior is energy-efficient in an environment where calories can be hard to come by.

As yardsticks to measure the effectiveness of information retrieval there exist those called 'recall ratio' and 'precision ratio'.