effectiveness

Etymology

effective + -ness

noun

1. The property of being effective, of achieving results.
   The effectiveness of the drug was well established.
2. The capacity or potential for achieving results.
   The problem with these precedents is that the Security Council did not authorize intervention in Syria, and an intervention there will thus harm, not help, the Council’s credibility and effectiveness. August 31, 2013, Jack L. Goldsmith, “What Happened to the Rule of Law?”, in New York Times
3. The degree to which something achieves results.
   He questioned the effectiveness of the treatment.
   United were having more possession but a sign of the effectiveness of Liverpool's defence was that it took the visitors 76 minutes to force Mignolet into serious action, when he dived to punch away a shot from substitute Nani. 1 September 2013, Phil McNulty, BBC Sport