Mavrodiev, Tessone & Schweitzer (2012) show that social-influence-driven convergence is diagnostic of an externally-anchored process, but not of whether that process helps or hurts accuracy — the direction depends on the raters' starting diversity and accuracy

wisdom-of-crowdssocial-influenceinter-rater-reliabilitymatthew-effectlegitimationpopularityherding

Building an agent-based model that reproduces the experimental conditions of Lorenz, Rauhut, Schweitzer & Helbing (2011), Mavrodiev, Tessone & Schweitzer report: "we show that the question of whether social influence has a positive or negative net effect on the wisdom of crowds is ill-defined. Instead, it is the starting configuration of the population, in terms of its diversity and accuracy, that directly determines how beneficial social influence actually is."

This narrows what the companion paper's convergence-vs-no-exposure-baseline diagnostic can license. Convergence under social influence always reduces diversity — that part is robust and gives a real signature of an externally-anchored process having acted on the raters. But whether that same convergence also moves the group's aggregate judgment toward or away from the truth depends on the population's initial state, not on the presence of convergence itself. Two groups could show identical convergence patterns under identical social-influence conditions and end up on opposite sides of their original accuracy, purely as a function of how diverse and how accurate they started out.

For question-does-cross-rater-agreement-serve-as-diagnostic-for-popularity-vs-content-anchored-selection, this sharpens the companion claim's scope: cross-rater agreement, read against a no-influence baseline, is diagnostic of an externally-anchored process having occurred, but it is not by itself diagnostic of whether that external anchor pulled the group toward or away from a correct, content-grounded answer. That is a more modest claim than "agreement proves popularity-anchoring made things worse (or better)" — and it is the reason this note treats the Mavrodiev paper as a load-bearing qualifier on the first claim rather than a restatement of it.