Table 5 The INTENTS framework for classifying spillover effects

Step #1: What are the expected outcomes of the intervention?

Step #2: At what level can spillover effects take place?

a) Who is targeted by the intervention?

b) Who is expected to change behaviour as a result of the intervention?

c) Whose behaviour/outcomes may change as a result of the intervention?

Step #3: Which spillover effects could the intervention generate?

a) Within-unit spillover effects (non-intended effect on a targeted unit)

b) Between-units spillover effects (intended effect on a non-targeted unit)

c) Diagonal spillover effects (non-intended effect on a non-targeted unit)

Step #4: What is the nature of the potential spillover effects identified in Step #3?

a) Is the spillover effect really different from the intended outcome?

b) Is the spillover relevant and related to the goals of the intervention?

c) Is the spillover effect consistent with the time frame of the intervention?

d) Is there a credible mechanism for the spillover?