Figure 4. A test of accuracy applied to four species diversity estimators. Each point represents a species inventory of terrestrial trees, arthropods, or tetrapods drawn from the Ecological Register (Alroy, 2015). The logged x-axis shows estimates based on the original, complete inventories; the logged y-axis shows estimates based on estimates recomputed after randomly excluding half of the individuals in each inventory. Diagonal lines are lines of unity, so scatters centered below the lines indicate bias. (A) Fisher’s α (Fisher et al., 1943). (B) Estimates based on fitting the scaled odds distribution (eqn. 10). (C) Estimates based on fitting the expedistribution (eqn. 16). (D) Estimates based on the Chao 1 index (Chao, 1984).