2.3 Your extra euro

There are two ways to ask whether a donation or a job is a good idea. The first is "is this a good organisation?" The second is "what difference does my contribution make?" They can have different answers.

Suppose a vaccination campaign is fully funded for the year. An extra donation might sit in reserve or pay for something less important. Now suppose a similar campaign has a gap, and without more money one district will be skipped. The same donation does far more there. Economists call this thinking at the margin: what counts is the effect of the next euro, hour or person, not the average effect of everything that came before.

The margin moves when other funders move. That happened on a large scale in 2025.

That figure is a model, not a count. Models like it rest on assumptions about which programmes stop and what replaces them. But the direction is clear. When large funders withdraw, programmes that were fully funded have gaps again, and an extra euro in global health can achieve more than it did the year before.

The general lesson goes beyond aid budgets. How neglected a problem is changes over time, and with it the value of the next person or euro. The same reasoning applies to careers, as you'll see in Unit 5.