Fig. 1From: Determination of ED50 and time to effectiveness for intrathecal hydromorphone in laboring patients using Dixon’s up-and-down sequential allocation methodScatter plot demonstrating dosages reported as effective (solid) and ineffective (hollow) for all 20 participants. The horizontal line represents the ED50 and was determined to be 10.9 mcg (95% CI +/−1.2 mcg)Back to article page