Existing methods for discovering business process simulation models from execution data (event logs) assume that all resources in a pool have the same performance and share the same availability calendars. This paper proposes a method for discovering simulation models, wherein each resource is treated as an individual entity, with its own performance and availability calendar. An evaluation shows that simulation models with differentiated resources more closely replicate the distributions of cycle times and the work rhythm in a process than models with undifferentiated resources. The paper is available at: https://link.springer.com/chapter/10.1007/978-3-031-16103-2_24

1. Business Process Simulation with Differentiated
Resources: Does it Make a Difference?
Orlenys López Pintado
Marlon Dumas
September 15, 2022 - BPM’22
PIX Project

2. Undifferentiated Or Differentiated Resources?
4 Clerks
Same Availability
Same Performance
Differentiated Availability
Differentiated Performance
Senior Clerk
Junior Clerk
Pooled Allocation
Unpooled Allocation
2
Inter-arrival
Times
Branching
Probabilities

3. Business Process Simulation
Simulation Model
Event Log
Metrics
Waiting Time
Processing Time
Cycle Time
Idle Time
Resource
Utilization
BIMP
3

4. Business Process Simulation
What would be the cycle time of a process
if the number of daily new cases increases by 20%?
What if a resource become unavailable for a long period?
What if a resource is replaced by another with lower performance?
What if a resource changes availability from full-time to part-time?
4

5. Research Question and Contributions
Do pooled allocation, undifferentiated performance and availability affect the accuracy
of a business process simulation model, and if so, to what extent?
1. A business process simulation approach with differentiated resources –
Unpooled allocation, Differentiated Performance, and Differentiated Availability
PROSIMOS
2. An automated method to discover a simulation model with differentiated resources from
event logs
Proposal
https://prosimos.cloud.ut.ee (Online)
https://shorturl.at/FNPS9 (Screencast)
5

6. Discovering Resource Availability
00:00 01:00 02:00 ….. 08:00 09:00 ….
23:00
Monday
00:00 01:00 02:00 ….. 08:00 09:00 ….
23:00
Sunday
.
.
.
.
Junior Clerk 06/06/2022 – 08:17:03  Monday – 08:00 to 09:00
What Granule Candidates to keep?
Confidence (task-conditioned)
Support
Resource Participation (task-relative)
How many Mondays from 8:00 to 9:00?
How many timestamps covered by any calendar granule?
How many resources to keep?
6

7. Discovering Resource Availability – Task Allocation
What if unallocated task?
Group By Max Disjoint Intervals
No Yes
7

8. Discovering Resource Performance
Task Instance: Check Credit History
Star
t
End
C1 C2 C3
Processing Time = End - Start
Idle
Processing Time = C1 + C2 + C3
What if not enough Points
(i.e., task instances processing
times)?
Best Fitted Distribution
Aggregated Distribution
8

9. Inter-Arrival and Branching Probabilities
Inter-Arrival
1. Filter and Sort first (start) event of each trace
2. Discover Inter-Arrival Calendar
3. Discover Best Fitted Distribution (difference between consecutive cases)
Branching Probabilities
1. Reply event log over process model
2. Compute probability on (Split) Inclusive and Exclusive gateways
9

10. Experimental Evaluation
10 Event Logs
10
Synthetic Real Process
Unpooled Allocation Differentiated
Performance
Differentiated
Availability
SP-NP-NA
MP-NP-NA
MP-DP-NA
MP-NP-DA
SP-DP-DA
5 baselines

11. Earth Movers’ Distance metric (EMD), which measures the minimum cost of turning one discretized
distribution (i.e., histograms) into another, penalizing each transformation by their distance.
EMD – Cycle Times:
EMD – Work Rhythm:
11
00:00 01:00 02:00 ….. 08:00 09:00 10:00 …. 22:00
23:00
15.09.2022 1 0 35 50 58 2 0
1 0 60 50 40 2 0
0
20
40
60
80
0
20
40
60
80
Cycle times grouped into 100 equidistant bins
0
100
0
100
Real Log Simulated-Log
Experimental Evaluation

12. Experimental Results
EQ1.What impact does unpooled resource allocation have compared to pooled allocation?
Unpooled models offer the best results under complete differentiation of resource performances
and availability. Still, they perform more poorly in the presence of undifferentiated resources.
EQ2 What impact does differentiated resource performance have compared to
undifferentiated performance?
EQ3 What impact does differentiated resource availability have compared to
undifferentiated availability?
Differentiated performance – Best (on average) Estimating Work Rhythm
Differentiated availability – Best (on average) Estimating Cycle Times
Differentiated performance and availability – Best Results Overall
12

13. Summary
2. Replace curve-fitting on Inter-Arrival Discovery
1. Discover calendar with non-weekly periodicity
3. Discover Optimal parametrization
13
Future Work
Proposal:
A business process simulation approach with differentiated resources profiles
Unpooled allocation,
Differentiated Performance
Differentiated Availability
PROSIMOS: Discovering and Simulating Business Processes With Differentiated
Resources

14. Business Process Simulation with Differentiated
Resources: Does it Make a Difference?
Orlenys López Pintado
Marlon Dumas
September 15, 2022 - BPM’22
PIX Project