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Chapter 4. Requirements
Furthermore, the user should have the possibility to export the values in {T (c) | c ∈ C} to a
comma-separated text-file.
Arrival rate of cases
The arrival rate of cases is equal to the number of cases that arrive to the process per time
unit. Given replay output L and case c, the arrival time T 0 (c) of case c is:
M IN(x∈L
∧ case(x)=c)
time(x)
The (average) arrival rate of cases to the process then is:
#C
M AXc∈C T 0 (c) − M INc∈C T 0 (c)
Number of cases
The number of cases in the log should also be available to the user. This number is equal to
#C .
Number of fitting cases
To give the user an idea about the conformance between the Petri net and the event log, the
number of cases that ‘fit’ in the Petri net should be given as well. The fitting cases are those
cases in which no transition fails execution during log replay. The number of fitting cases can
be defined as: #{c∈C| @x∈L (case(x)=c∧f ailed(x)=true)}
For more detailed information about the conformance between the used Petri net and event
log, the Conformance Checker plug-in of the framework should be used.
4.2.3
Place-related KPIs
Firing of transitions during log replay is atomic, since events have a timestamp and not a
duration attached to them. Therefore we can say that the tokens, that represent a case during
log replay, spend time in places. In this section, the KPIs that are related to places will be
discussed.
Since the timestamp at which transitions fire is known, also the creation timestamp of each
token that is added to an output place of the transition is known. For each token that is
consumed by the firing transition, the consumption timestamp is also known. However, when
an input place of a firing transition contains multiple tokens, then we cannot tell which token
is removed exactly. A pseudo-random function with equal weight is used to select a token
from each input place. Note that this may affect the KPIs defined below.
Sojourn time of place p
The sojourn time of a token in place p is equal to the total time a token spends in p, i.e. the
time between creation and consumption of the token. Statistical values should be calculated
for the sojourn time of place p, based on the sojourn times of all tokens that are added to place
p during log replay. This calculation can be done in a similar manner as for the throughput
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