Efficacy
Efficacy refers to the ability of an intervention to produce a beneficial effect in a highly controlled environment, such as a clinical trial. Essentially, it measures the intervention’s performance under ideal conditions.
Effectiveness
it is equally important to assess the intervention’s effectiveness in real-world settings, where conditions are not as controlled as in a clinical trial. Effectiveness measures the ability of an intervention to produce a beneficial effect in practical circumstances.
Efficiency
This refers to the cost-effectiveness of the intervention or the extent to which its benefits outweigh its costs. In other words, it measures the intervention’s value for money and is important when deciding whether to implement a particular intervention.