You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is When an intervention is applied to community to evaluate its usefulness, it is termed as a trial for - and explain in detail?
EVALUATION OF HEALTH SERVICES:

Efficacy: Is the effect or usefulness of an agent/ drug/ vaccine under ideal ‘controlled laboratory’ conditions
Effectiveness: Is the effect or usefulness of an agent/ drug/ vaccine in real life community situations
Efficiency: Is the measure of relationship between the results achieved and the effort expended in terms of money, resources and time

– Efficiency: Output/ Input
– Evaluation of efficiency:
1. Cost-benefit analysis: Both input as well as output is in monetary terms
2. Cost-effectiveness analysis: Input is in monetary terms whereas output is in terms of ‘no. of lives saved'.