What happens when an Activity uses itself as a predecessor?

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Lou Keller asked Aug 26, '16 Matthew Gillespie answered Aug 26, '16

What happens when an Activity uses itself as a predecessor?

The attached model, "Acuity.fsm," was designed some time ago to show how to model the fact that the passage of time affects a patient's acuity. In a nutshell, when patients classified as "Immediate" or "Urgent" wait too long to be seen or treated, their acuity increases from one classification to the next until they eventually die from lack of medical treatment or attention. It's a vital aspect of mass casualty modeling. If you examine the Immediate and Urgent Tracks in the attached model, you'll see that Activities 70, 80 and 100 use themselves as predecessors. While 70 and 80 are also started by Activity 60 - based on percentages - Activity 100 isn't. Two questions - 1. What happens when an Activity uses itself as its own predecessor? and 2. How is Activity 100 activated? acuity.fsm

Software Version:

FlexSim HC 5.0.12

healthcare predecessors activity activation

acuity.fsm (260.2 KiB)

Answer 1 · 2016-08-26T17:38:39Z

Matthew Gillespie answered Aug 26, '16

In previous versions, before the Predecessors field had the Use Predecessors checkbox, you would write in the activity's own number as the predecessor if you didn't want it to be started using predecessors. The activities in this model are being started by Next Activity fields or the Start Activity command and so the predecessor field is "turned off". So, it's equivalent to un-checking the Use Predecessors box, but less intuitive as to what it means.

Activity 100 is being started by the Patient Condition Changes field of ObservationRoom1. IF you open up the code editor you'll see this code at the bottom:

// if the patient has progressed from acuity 4 to 5, we need to transport him to the morgue
if(condition_value >= 5)
{
	colorblack(patient);
	startactivity(patient, 10);
}

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