Table 2.

Statistics for temporal leaf width decrease based on 10 000 bootstraps (latitude covariate).

years included	n	coefficient	upper 95% CI	statistically robust?
1880–1950 (‘pre’)	30	−0.05	0.004a	no
1950–2011 (all latitudes; ‘post’)	232	−0.01	−0.002	yes
1880–2011 (‘all’)	262	−0.02	−0.007	yes
1950–2011 (northern latitudes; ‘north’)	68	−0.02	−0.002	yes
1920–1980 (‘mid’)	201	−0.02	−0.008	yes
1920–2011 (‘other’)	254	−0.01	−0.003	yes
categorical: pre-1950/post-1990	66	−0.98	−0.071	yes

^aPositive value indicates insufficient confidence in width decrease, as 95% CI overlap zero.