Intermediate indicators should be included in evaluations to track the theory of change. It should be noted that even though no change in diarrhea was detected, an intermediate indicator (residual chlorine levels) did show an improvement. The longer the chain of events between the intervention and the measured outcome, the harder it can be to determine whether there was an impact. Using indicators (e.g. residual chlorine) that link intervention (water infrastructure) to outcome (diarrhea) should be replicated in future evaluations to understand how far down the chain the effects of the intervention were felt.
Lesson Learned