Boxplots comparing three diversity metrics across three datasets when cover values are estimated directly in percent, based on the 13-step Londo scale, a 7-step Braun-Blanquet scale, and the 5-step Hult-Sernander-Du Rietz scale. Back-translation from the ordinal scales to percent was done with the geometric means of the class borders. The rows correspond to the datasets A, B and C. The asterisks indicate the Bonferroni-corrected p-values from paired t-tests of the values achieved with the ordinal scales vs. the values on the original scale.