Model 1a  Processes & Activities
Goals of this lesson

Getting to know IYOPRO’s simulation feature

Setting up a simple simulation configuration

Running a simulation
HowTo
Have a look at our first tobesimulated model. It consists of a TimerStartEvent, two successive activities and an EndEvent.
First Step: The Interarrival Time of the start event
The simulation needs an interarrival time, which specifies the starting intervals between new process instances:

Make sure, you selected the Simulation option from the Property Set dropdownbox (See highlighted area in Figure 5 below)

Click the start event

Now click the button right of the empty field of the Interarrival Time option under the MustHaveProperties (See Figure 3 below)

The Time Editor will show up (See the Figure 2 below and see Assigning Interarrival Times for detailed information)

Select the Constant Distribution

Set a constant value of 2

Close the Time Editor by clicking OK

The Interarrival Time of this specific process is now set. It will always start by an interval of 1 time unit.
Second Step: The activities' durations
Since activities are time consumptive, they need a stochastic distribution that represents this time consumption in the simulation.

Make sure, you selected the Simulation option from the Property Set dropdownbox

Click the first activity in the sequence flow ("Constant duration")

Now click the button right of the empty field of the Duration option under the MustHaveProperties (See Figure 4 below)

The Time Editor shows up

Select the Constant Distribution

Set a constant value of 1

Close the Time Editor by clicking OK

As you might notice, the functionality of setting up an Interarrival Time and a Duration works alike.
So far we parametrized the simulation with constant values, which mostly do not resemble the circumstances in reality. Therefore, we will bring in some dynamics in our model by setting up a real stochastic distribution for the second activity’s duration.

Repeat the steps 1 to 3 from above for the second activity

The Time Editor shows up

Select the Normal Distribution

Set a Mean value of 1

Set a Standard Deviation value of 0.5

Close the Time Editor by clicking OK

Third Step: Starting the simulation
Since the end event does not contain any simulation related options (see Figure 6 below), we now have set up all necessary properties to start the simulation. Now just click the green Analyze button (in the middle of IYOPRO’s top menu bar) and wait for the Progress Bar to finish.
Report
When the simulation has finished, you will get a report with a set of values for your experiment. See below for the run configuration, which we set up to receive the report statistics from below.
Please refer to the section Experiment Results for more information on the report specific data.
Run configuration

Stochastic Seed: 12345

Simulation start date: 1/1/2014 12:00:00 a.m.

Simulation stop time: 48

Simulation stop time unit: Hours
Report statistics
The report of this model consists of three parts:

Process details

Activity details

Event details
Actually the report consists of four parts. The first part contains the model description and the settings of the experiment run. This enables you to reproduce the report by reconfigure the simulation with the given information. 
Process details
Here the report provides statistics for the processes' cycle times. They are visualized by histograms (Figure 7) and Boxplots (Figure 9). But there are also tables with the exact statistics (Figure 8 and Figure 10).
Result

The process cycle times from Figure 8 deliver the statistics for the process' cycle time

We notice, that the cycle time’s mean value is at around 2 hours and 2 minutes

with a standard deviation of about 29 minutes


The lowest cycle time amounts to 1 hour and 6 minutes (MinValue)

The highest cycle time amounts to 3 hours and 9 minutes (MaxValue)

This is also represented in the histogram

There is only one process instance whose cycle time was higher than 3 hours



The histogram classifies the finished process instances into time intervals

As you see, 22 process instances have a cycle time between 1 and 3 hours

There is only one outlier


Additionally the boxplot from Figure 9 tells us that the process instances' cycle times concentrate in a range between 1 hours and 30 minutes and 2 hours and 30 minutes

Also see the last 3 columns of the table from Figure 8 (Lower and upper quartile and median).


The table from Figure 10 illustrates statistics about the number of simultaneously active process instances.

On average there was only one process instance active (Mean)

There have been at most 2 process instances active at the same time (Max)

Activity details
In this part of the report you will find all the statistics of the activities.
Activity runtimes and waiting times

We notice that "Constant duration" activity really was constant (1st line of the activity runtimes and waiting times table from Figure 11)

Check out the "Stochastic distributed duration". It almost reaches our configuration of a normal distribution with a mean value of 1 and standard deviation of 0.5

Note that, the longer the simulation runs the more this statistic will converge to our actually set normal distribution


Do you notice something else?

Yes, if you add up both activities' mean value you will get the process' mean cycle time as a result

The same goes for the standard deviation, minimum and maximum values

Unfortunately this only that simple, because our model is also very simple

Concurrently existing activities

We notice that there has been 0.5 activities of "Constant duration" active at the same time

How is this even possible? You cannot have half an activity active!?

These values are still just statistics for a certain period of time

Explanation

Our process starts every 2 hours

The "Constant duration" activity works constantly for 1 hour

So, there is a difference of 1 hour

The constant activity finishes and the next process instance starts after 1 hour and will therefore reach the constant activity in 1 hour

That is why  in statistical matters  this activity is only active half of the time



The same explanation applies for the stochastic activity
Distributions

The Distributions table from Figure 11 simply shows the Distributions' configurations, which we set

Also you can find the number of value drawings from the distribution (Obs)

And its individual seed is also depicted in the table

Note that this seed depends on the general seed

Event details
This part of the report presents the events' statistics, see Figure 12.
Event counter

In this table you can see how often an event has been executed (Obs)

The end event of our process has been executed 23 times, which matches the number of finished process instances in the process details
Interarrival times

This table shows the interarrival times of events

This means, we count the time between the execution of the same event and then erect this statistic


Our start event has an interarrival time of 2 hours

This matches with our configuration for the start event (Constant distribution with a value of 2)


Our end event’s interarrival time has a mean value of 1 hour and 58 minutes

Please do not confuse yourself by thinking that the end event’s interarrival time should be the same as the process' cycle time

These times' values are similar to each other, but they are mostly not equal
