Figure 4From: Detecting contaminated birthdates using generalized additive modelsThe smoothing term s 2 ( d ) in Equation (2). The dashed lines show 95% confidence interval of the estimate. It suggests that before year 1920, there were more weekend births than weekday births. The number of weekend births has decreased since year 1960, very likely due to wider adoption of elective Caesarean section.Back to article page