Fig. 4From: Using Z-score to optimize population-specific DDH screening: a retrospective study in Hangzhou, ChinaThe α angles and ages of the false-positive population. a The first examination with positive results. b The later examination with negative results. The mean value of Z-score model is shown in solid line. One SD (standard deviation) and 2 SD value of Z-score are shown in dotted and dashed line. The red and green colors represent male and female infants respectivelyBack to article page