Common questions asked by clinic management are: "How long do our patients wait before being seen? How long are they at the clinic? How big does my waiting room need to be? ".

In this case study we are going to consider a simple health clinic model in which patients arrive every 20 mins on average. Once the doctor is ready to see them they take 2 minutes getting to the doctor’s office and treatment takes between 5 and 30 minutes, with the usual treatment time of 10 minutes and the average treatment time of 15 minutes.

The goal of this simulation study is to analyse the effects of different arrival and service distributions on the average time patients spend:

1. waiting for treatment; and
2. in the clinic; and the average length of the patient queue (which informs waiting room size).

1. Background – problem description
2. Objectives of the study
3. Expected benefits
4. The CM: inputs, outputs, content, assumptions, simplifications
5. Experiments to run

Components 1 (Background – problem description) and 2 (Objectives of the study) are given in the Problem Description section (see paragraph describing the goal of the simulation study to identify study objectives).

The Expected benefits (component 3) are a virtual environment for evaluating patient waiting times, total time patients spend in the clinic, and the number of patients waiting for treatment. This environment can be used to experiment with changes to the clinic, including the effect of variability in arrivals and treatment times.

The CM content is specified using the following components:

1. Component List
2. Process flow diagram
3. Logic flow diagram
4. Activity cycle diagram

Component List

The components of the Simple Health Clinic model are:

• Patients with their (inter)arrival times
• Doctor with their treatment times
• Waiting room with its capacity

Process flow diagram

Logic Flow Diagram		Activity Cycle Diagram

Once the content has been established (note this is usually an iterative process) we can identify the inputs and outputs: interarrival times, treatment times, waiting times (Patient arrives to Doctor sees patient), total clinic time (Patient arrives to Outside), number in waiting room.

Assumptions are used to define stochasticity (e.g., Exponential interarrivals, Triangular treatment times) and the simplifications keep the system simple (e.g., one doctor on all day, no registration, no prioritisation).

Next, we create the components: Patients; Doctor; and Waiting room. We expand the Process Flow model palette (in the Model Builder) window and drag the SimEntity object onto the view (View1 window).

Then, select SimEntity1 from the Process Flow > SimEntity object list in the Object Selector window and wait briefly until you can change the name of the object to PatientEntity.

Now, we want an image to use for a patient. Download patient.png (icon made by Freepik from www.flaticon.com). Then, right click on PatientEntity and select Change Graphics. Click on Import and navigate to your downloaded patient.png, import it and accept the change. You will see patient.png looking a little “flattened” as it is essentially a “tile” in 3D.