Provision should be made to compare results from the same scenario but different run lengths or replications. The required run length to produce usable results depends on the process model structure, the amount of variability, and the objective. A replication shares the same scenario configuration and runs for the same time period, but uses an alternate random stream.
Levels are not interdependent, you can start at any level if you have the required process data. By default, Simulate mode starts at Level one, the first time a Simulate is run for the process model. The first and most basic level of simulation to evaluate the structure of the process diagram.
It also needs the value of the trigger counter contained in the Start Event shape. The results show all paths that were activated during execution and whether all tokens were actually completed.
Process Validation
Time Analysis
Apart from the data entered in Process Validation, estimated timings (service times) of each activity and the interval time between token generation are required. This level of detail provides a reliable estimate of how the process will perform in operation. In addition to the data entered in Time Analysis, this level includes the definition of resources (and/or roles): how many are available and where they are used.
Due to the involvement of resources, activity times should be adjusted to represent actual work time; delay due to unavailability of staff will be expressly stated. The time spent, the time spent busy or free for each type of resource is displayed.
Resource Analysis
In addition to the data entered in resource analysis, it includes the definition of resource calendars.
Calendar Analysis
Process Validation
The first level of the simulation validates the Process Model, making sure that the process goes through all the sequence flows and behaves as expected. In the Process Validation level, you will notice that only Start Events and Gateways are enabled for editing. Select the start event of the process and click the Gear icon on the pie menu.
Once the required data for this level has been defined, click the Run button to execute.
Running the simulation
Results
Set the Max. Arrival Count = 1000
Define the Probabilities for All Outgoing Paths
Click the Run and Start button
Analyzing the Results
Analyzing the results, we come to the conclusion that something is wrong:. 1000) created at the start event of the process is different from the sum of tokens.
Solution
- Time Analysis
That is, it defines a service time period from when a token arrives at an Activity or Event until it is executed. Select Clock in the pie menu and enter a processing period in the Time Control. You have the option of defining the processing time as a constant by entering values in .
In the following figure, the token processing time in a particular activity is normally distributed with a mean of 5 minutes and a standard deviation of 3 minutes. For a general insight into the processing times, we decided to perform a time analysis in the emergency service. To do this, click on the start event and then click on the gear icon in the cake menu.
For this example, the expected time between reports is 5 minutes, so set the time to that value.
Define Trigger Times
Click Activity, select Time from the cake menu, and set a value for the Time control. In the following image, the processing time for the first activity is set to 4 minutes.
Define the Activities' processing times
Run the Simulation
Select Results to View the Outcome
Analyzing the results
- Resource Analysis
Remember that a resource is defined as the person, equipment or space required to perform a specific task. In the previous level, time analysis, we assumed infinite resource capacity, which means that activities are capable of processing an infinite amount. This results in bottlenecks and increased cycle times, thereby reducing process capacity.
The purpose of this analysis is to identify and minimize the impact of these limitations. Resources: Remember that a resource is a person, equipment or space that is needed for the performance of a specific task. To define availability and cost of resources, select the Resources option found in the ribbon.
Resource availability determines how many resources of a specific type you have in total (not for a specific activity). After you have defined the process resources, you must define how many are required. To define the resource requirements for a task, click the task and select the resource icon from the pie menu.
The AND/OR selection mode is available to define whether all the selected resources are required by the task at the same time or only one at a time. For each selected resource, you must define how many of them will be used in the task. Activity cost: The cost of performing an activity, i.e. how much an activity costs when it is performed.
To define the cost of performing an activity, select the Activity and click Costs on the pie menu. Once the required data has been entered, click the Run and then Start button to run the simulation.
Running the Simulation
For the Resource Analysis level, the simulated output results will contain the following Process and Resource information. Standard Deviation: Shows the standard deviation of the average time a task had to wait for a resource. Total Fixed Cost: Shows the total cost of performing a task during the simulation run.
For example, here we define that the second activity requires a nurse to be performed. Pick up patient Fully equipped ambulance 1 Arrive at patient location QAV Basic ambulance 1 Arrive at patient location BA Rapid attention vehicle 1. Here we define the cost of performing the Manage patient enrollment activity is 1 dollar.
Click Run and Select Start
The results of a resource analysis give us a general insight into the cycle time of the process.
Analyzing the Results
- Calendar Analysis
Compared to the best-case scenario achieved at the previous level, the inclusion of resource constraints significantly increased cycle times. The increase of 2,823 US offsets the benefit of reducing the average waiting time to 179.5 minutes. In addition to the resource constraints discussed in the previous level, we also need to consider the effect of resource availability over time to gain a better understanding of the actual process.
Recurrence Start: Specifies the start date of the time period to which the calendar applies. Recurrence End Specifies the end date of the time period in which the calendar is valid. In addition, at this level you must specify resource availability for each defined calendar.
In order to analyze the impact of calendars in Patient Assistance, the Emergency Department decided to analyze calendars. Start Time: This calendar starts at 22:00 (see table above), so this is the start time. Duration: This calendar starts at 10:00 PM and ends at 6:00 AM, making the calendar 8 hours long.
Repeat Pattern: This calendar repeats every day, so select Daily and enter 1 in the field next to it. Repeat Start: This calendar always applies so that the start date is the same as the start date of the simulation.
Create the three calendars (working shifts)
Through the Resources option
Click the Run button
Analyzing the results
The increase of the maximum time from 35 to 39 minutes can be explained by the existing waiting times for some process activities, which did not exist at the previous level. Remember that this resource performs two activities in the process: triage classification and patient intake management. From the results of the Process, we can conclude that the utilization of nurses is not full, as there are no waiting times for the related activities.
