When Mini-Publics Aren't Representative, Their Legitimacy Gains Vanish

Why This Question Matters: Many advocates promote deliberative mini-publics—small, randomly selected groups that advise or decide on public issues—as a way to boost democratic legitimacy. Micha Germann asks whether the real-world limits of representativeness (small sample sizes and non-response biases) weaken the public credibility of these bodies.

What the Study Tests: Germann reports a pre-registered survey experiment (N = 1,308) that evaluates how deviations from statistical representativeness affect citizens' legitimacy beliefs. The central outcome is perceived process legitimacy: how fair, inclusive, and authoritative respondents view a decision-making process that involves a mini-public.

How the Experiment Works: Respondents completed a survey experiment in which the presence of a mini-public and the degree of its statistical representativeness were systematically varied. The design isolates whether the involvement of a mini-public raises legitimacy perceptions and how sensitive that effect is to small versus large composition biases that mimic nonresponse and small-sample noise.

Key Findings:

• The inclusion of a randomly selected mini-public substantially increases perceived process legitimacy compared to decision-making without one, aligning with prior work.
• Even modest departures from representativeness—small demographic imbalances—substantially reduce these legitimacy gains.
• Larger representativeness biases can eliminate the legitimacy advantage altogether: when mini-publics appear clearly unrepresentative, respondents do not view decisions as more legitimate.

What This Means for Reformers: The results temper hopes that mini-publics are an easy fix for legitimacy shortfalls. The legitimacy payoff depends critically on credible representativeness; small-sample variability and nonresponse can undercut public confidence. Practitioners should therefore prioritize sampling procedures, participation incentives, and transparent communication to sustain the perceived fairness and authority of mini-publics.