Sentence:  The throughput time on the above patient, when using the appointment time to <WSD>check-out time</WSD> ratio, is 75 minutes. By using check-in time to <WSD>check-out time</WSD>, as purists would, the throughput time is 80 minutes. However, the face-to-face time is only 20 minutes; therefore, the patient would perceive value for only 25 percent of the visit. 
Meaning of the word marked with <WSD> tags:  The time when one checks out (any sense).