Figure 1
The image contains two line graphs side by side. The left graph, titled Before matching, shows the kernel density curves for the control group and the experiment group before matching. The x-axis represents the propensity score ranging from 0 to 0.8, and the y-axis represents the kernel density ranging from 0 to 3. The control group is represented by a solid line, and the experiment group is represented by a dashed line. The curves show different distributions before matching. The right graph, titled After matching, shows the kernel density curves for the control group and the experiment group after matching. The x-axis and y-axis have the same ranges as the left graph. The solid line represents the control group, and the dashed line represents the experiment group. The curves show similar distributions after matching, indicating that the matching process has balanced the distributions between the two groups.Kernel density curve