Phase 1 - Define

1.2 Define your target population

Even if your SIB development process does not begin with a logic model or theory of change, it is important to make sure your target population is precisely defined:

  • It helps all stakeholders involved to understand the focus of the intervention. It makes conversations with potential commissioners - and in the next phase, with investors – more productive
  • The choice of target population will influence how strategic your SIB is to a commissioner: the population affects the outcomes you forecast, and therefore the savings or other potential benefits that might interest a commissioner

Also bear in mind that in the delivery phase of your SIB, you’ll be referring to this definition when deciding which participants to recruit.


A precise definition of the target population helps to safeguard against the risk of gamesmanship.

The more precise the definition of the target population, the narrower the scope for these tactics. While you might not plan on them, it’s safest not to rely on good intentions, especially with a long and complicated supply chain. Evaluations can pick up on poorly defined target populations at the end of the programme, even if the initial design and set up has not.

Cherry picking – selecting participants who are most likely to achieve the outcomes or easiest to reach. Also known as ‘cream-skimming’.

Parking – ignoring those least likely to achieve the outcomes, or those who are most expensive to reach.


Next: 1.3 Define your programme outcomes