

Ask HN: efficiency, efficacy, effectiveness?! - JBiserkov

The more I read about the subject the more confused I become.<p>I tried to identify the types of those "functions" and work out "definitions". Please correct/expand.<p><pre><code>  Effectiveness 
  x -&#62; Bool
  
  Efficacy
  x -&#62; (0, 1)
  
  Efficiency
  x -&#62; (0, 1)


  Effective = 100% efficacious

  Efficiency = essential / (essential + non-essential)</code></pre>
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stonemetal
Efficacy is the noun form of Effective. Efficacy = Effectiveness. Efficiency
is the ratio of output to input. Though it seems there is some slight
variation in their use in different fields.

