Fig. 4From: Assessment of research waste part 1: an exemplar from examining study design, surrogate and clinical endpoints in studies of calcium intake and vitamin D supplementationNumbers of publications of randomised clinical trials of vitamin D supplements over time classified according to the clinical or most clinically relevant surrogate endpoint reported in the Abstract. Left panel: trials with bone mineral density or fracture. Right panel: all trials classified according to clinical or surrogate endpoints. 25OHD- 25-hydroxyvitamin DBack to article page