The effectiveness of an intervention, from single treatments through to services including the professionals within them, is the degree to which the desired outcomes are achieved in clinical practice.
Source: Gray M (2009) Evidence-Based Healthcare and Public Health. How to make decisions about health services and public health. 3rd edition. Churchill Livingstone Elsevier. Page 193.
Two examples of the term in use:
In summary, the evidence suggests that home care is a service that is highly valued by many carers. In addition, the more rigorous research evidence also suggests that home care contributes to caregiver welfare, although it may not be the most effective form of intervention for this purpose.
Pickard L (2004) The effectiveness and cost-effectiveness for support and services to informal carers of older people. A review of the literature prepared for the Audit Commission. Personal Social Services Research Unit, London School of Economics. http://www.lse.ac.uk/LSEHealthAndSocialCare/pdf/LitReview-Older-Effectiveness-final.pdf
The effectiveness and cost effectiveness of population based dietary approaches to prevention of cardiovascular disease in the UK are less clear.
Barton P, Andronis L, Briggs A et al (2011) Effectiveness and cost-effectiveness of cardiovascular disease prevention in whole populations: modelling study. BMJ 2011; 343 doi: https://doi.org/10.1136/bmj.d4044 (Published 28 July 2011) Cite this as: BMJ 2011;343:d4044