When an intervention is applied to community to evaluate its usefulness, it is termed as a trial for -

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'.