Where does effectiveness collide?

The degree to which a medical intervention improves outcomes when it is used under ordinary, everyday conditions, with the mix of patients, clinicians, and adherence found in routine practice. It is defined by contrast with efficacy, which is how well the same intervention performs under the controlled, ideal conditions of an explanatory randomised trial: Singal, Higgins, and Waljee's 2014 A primer on effectiveness and efficacy trials set out this pair and the pragmatic designs that measure the real-world quantity, and Haynes's 1999 framing asked in turn whether a treatment can work, does work, and is worth it. The referent is the observed benefit of a therapy in the field, and it is not an organisation reaching its goals, a ratio of health gained to money spent, or the learning a teacher adds.[1][2]

Unit

Improvement in a health outcome under routine-practice conditions

Recovery means

Not applicable

Measured by

Estimated in pragmatic or effectiveness trials and observational studies that enrol typical patients and follow usual care

The degree to which an organisation attains the ends it is set up to reach, treated as a central but contested and multi-dimensional property of the whole organisation. Cameron's 1978 Measuring organizational effectiveness in institutions of higher education showed that the construct has no single agreed operational form and must be assessed across several domains, while Yuchtman and Seashore's 1967 A system resource approach argued it should be read as an organisation's ability to secure scarce resources rather than to hit fixed goals. The referent is a judgement about an organisation as a whole, and it must be kept apart from efficiency, which is the ratio of outputs to inputs, and from the clinical, economic, and educational meanings of the word.[3][4]

Unit

A rating of goal attainment across several organisational domains

Recovery means

Not applicable

Measured by

Assessed with multi-dimensional models, stakeholder ratings, and domain-specific indicators rather than one agreed metric

The amount of health outcome an intervention buys for a given amount of money, expressed as a ratio of added benefit to added cost and used to compare where scarce health spending does the most good. Weinstein and Stason's 1977 Foundations of cost-effectiveness analysis for health and medical practices laid out the method by which cost per unit of outcome, later standardised as cost per quality-adjusted life year, guides resource choices. The referent is a price-of-benefit ratio for an intervention, not the real-world clinical benefit on its own, an organisation reaching its goals, or a teacher's contribution to learning: two treatments can be equally effective in the clinical meaning yet far apart in this one.[5]

Unit

Incremental cost divided by incremental outcome, such as cost per QALY

Recovery means

Not applicable

Measured by

Computed in cost-effectiveness analysis as an incremental cost-effectiveness ratio against a comparator

The contribution a particular teacher or school makes to students' measured learning, isolated from what those students would have achieved anyway given their prior attainment and background. Nye, Konstantopoulos, and Hedges's 2004 How large are teacher effects? used an experiment to estimate this value-added contribution and to show that teachers differ substantially in it. The referent is a growth-in-achievement quantity attached to an educator, and it shares only the word with a therapy's real-world benefit, an organisation's goal attainment, or a cost-per-outcome ratio.[6]

Unit

Student achievement growth attributable to a teacher or school

Recovery means

Not applicable

Measured by

Estimated by value-added models that adjust outcomes for prior attainment, or by randomised assignment to teachers