Fig. 2

Procedures of data cleaning. a A few observations had appointments, who might come very late after registration, were excluded from our analysis. b We also discarded patients arriving late to prevent them from interfering with the result. c Since this study mainly shortened the time of the patients undergoing the laboratory test, the patients who did not have the test should be deleted. d The data of some patients recorded the time they got their medicine but the corresponding drug costs were missing. This part of data was deleted as missing value.e patients with illogical discrepancies was deleted. For example, a few patients could register and get medicine in just 1 min according to our calculation, which was impossible in our hospital