Fig. 2

SMOG (“simple measure of gobbledygook”) readability index (number of years of education needed for a person to understand a written text) of Cochrane Scientific abstracts (SA) (n = 158); Press releases (PR) (n = 162); Plain language summaries (PLS) in English (n = 156), German (n = 41), French (n = 101) and Croatian (n = 156); and Cochrane Clinical Answers (CCA) (n = 35). Error bars are 95% confidence intervals. The full analysis of readability dataset is available Additional file 1: Table S1 and S2. SMOG index for Croatian language was calculated according to the formula adapted to Croatian [17]. Statistically significant differences (Kruskal Wallis test and post-hoc Conover Iman test): for summary formats in English – PR vs SA and PLS, CCA vs. PLS, SA vs. PR and PLS, PLS vs. all other formats; for PLS translations – all comparisons were significant