Association between hospital adjusted rates [(O-E)/N] for surfactant use and mortality. This scatter plot displays hospital adjusted rates [(O-E)/N] of surfactant use on the x-axis and hospital adjusted rates of mortality [(O-E)/N] on the y-axis (note break in y-axis). Although there was an outlier hospital, the overall trend in the plot is consistent with an association between decreasing mortality and increasing surfactant use (Kendall's tau correlation coefficient of 0.37, p = 0.051).
Kaplan et al. BMC Health Services Research 2011 11:22 doi:10.1186/1472-6963-11-22