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There are three types of indirectness.
The first is uncertainty about applicability because of differences between the participants and treatments in studies and those of interest.
The second is uncertainty about the extent to which an effect estimate for a surrogate outcome reflects the effect for the important outcome that the surrogate is believed to.
The third is uncertainty due to an indirect comparison, between studies.
Indirectness is a reason for there being less certainty of the evidence for an effect estimate.
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