The Five Dimensions of Impact: An Overview

IRIS+ structures impact assessment around five distinct dimensions — What, Who, How Much, Contribution, and Risk — that together are intended to describe not merely whether some outcome occurred at all, but how meaningful, well-targeted, and genuinely attributable that outcome actually was. Read individually, each dimension is fairly straightforward to understand on its own terms. Applied together to a real, specific investment, they frequently pull in different directions, and the genuinely interesting analytical work lies in how a given assessment resolves those tensions, rather than in defining any single dimension in isolation.

What each dimension asks

What identifies the specific outcome itself — the particular change being measured, whether positive or negative, whether intended by the investment or an unintended side effect of it.

Who identifies the specific stakeholders actually experiencing that outcome, including importantly their starting condition beforehand, since the identical outcome — an income increase, say — means something meaningfully different for a population starting from severe poverty compared with one starting from a more moderate income level.

How Much captures scale, meaning how many stakeholders were affected, depth, meaning how much change occurred per stakeholder, and duration, meaning how long the resulting effect actually persists over time — three genuinely distinct sub-components that get reported, all too often, as a single blended figure that ends up obscuring which of the three is actually driving the headline number.

Contribution is the explicitly counterfactual dimension: what would plausibly have happened to this specific outcome without the investment at all, isolating the investment's actual, genuine causal contribution from outcomes that were already underway independently, or that would very likely have occurred regardless of this particular investment's existence.

Risk captures the likelihood that the claimed impact doesn't actually materialize as expected, or that it ends up being meaningfully overstated relative to what actually happens on the ground.

Where the dimensions conflict in practice

How Much and Contribution pull against each other most visibly and most often in real reporting. An investment can report genuinely large scale and depth figures — reaching many stakeholders, with substantial reported change per stakeholder — while simultaneously having quite weak Contribution, meaning the underlying outcome would very plausibly have happened through other channels regardless of this specific investment's involvement. A large, genuinely impressive-looking How Much figure paired with an unexamined or unreported Contribution dimension is a common pattern in impact reporting precisely because How Much is considerably easier to measure directly — simply count the stakeholders, measure the observed change — while Contribution requires constructing a genuine counterfactual estimate that's inherently harder to build well and considerably more uncomfortable to report honestly whenever that estimate turns out to be weak.

Who and How Much conflict in a somewhat different way: reaching a genuinely large number of stakeholders, which drives a strong How Much figure on the scale sub-component specifically, is often meaningfully easier among populations that are already comparatively easier to reach in the first place — better existing connectivity, somewhat higher baseline income, more physically accessible geography. This can mean that strong reported scale numbers are quietly correlated with a Who profile that's actually less well aligned with the investment's originally stated target population — typically the most genuinely underserved, hardest-to-reach stakeholders — without that particular drift ever becoming visible in the How Much figure taken alone. An investment quietly optimizing for reported scale over time can drift steadily toward an easier-to-reach Who profile without that drift showing up anywhere in the headline number being reported.

Risk is, in practice, the dimension most often reported as something of an afterthought, or omitted from summary reporting entirely, precisely because it's the one dimension among the five whose genuinely honest reporting tends to weaken the overall impact narrative rather than reinforcing it — acknowledging meaningful, real risk that the claimed impact might not materialize as expected sits uncomfortably next to the other four dimensions, which are typically framed in more straightforwardly affirmative terms throughout a given report.

What this means for reading an impact assessment

An impact figure presented without any clear reference to which of the five dimensions it's actually describing is, in a real sense, providing considerably less information than it might initially appear to at first glance. A large How Much number says relatively little about an investment's genuine actual impact on its own, without corresponding information about Contribution — would this outcome have happened anyway, absent the investment — and about Who — reaching the genuinely intended target population, rather than simply a more conveniently accessible one. Assessments that engage seriously with all five dimensions, including the less flattering ones like Risk and a weak Contribution estimate, are making a considerably more complete and ultimately more defensible claim than those that report primarily, or exclusively, on whichever single dimension happens to look best in isolation.