 Assume the group must estimate or predict some real-valued quantity, such as inflation, income inequality, or global temperature. Here, \(\mathcal{A}\) is a real interval, e.g., \(\mathcal{\mathbb{R}}\) or \([0,1]\), containing the possible estimates. Let the group aggregate members’ estimates by taking their average (rather than their median, as in Galton’s 1907 classic paper on the wisdom of crowds). Formally,