Elsevier

Information Systems

Volume 71, November 2017, Pages 1-15
Information Systems

A comparative study of existing quality measures for process discovery

https://doi.org/10.1016/j.is.2017.06.002Get rights and content

Highlights

  • The feasibility of quality metrics for discovered processes is analysed.

  • It is analysed whether metrics related to the same dimension agree with each other.

  • It is analysed whether metrics are related to each other, or independent.

  • It is analysed to which extent some metrics are more optimistic.

  • It is analysed to which extent some metrics are more sensitive.

Abstract

Evaluating the quality of discovered process models is an important task in many process mining analyses. Currently, several metrics measuring the fitness, precision and generalization of a discovered model are implemented. However, there is little empirical evidence how these metrics relate to each other, both within and across these different quality dimensions. In order to better understand these relationships, a large-scale comparative experiment was conducted. The statistical analysis of the results shows that, although fitness and precision metrics behave very similar within their dimension, some are more pessimistic while others are more optimistic. Furthermore, it was found that there is no agreement between generalization metrics. The results of the study can be used to inform decisions on which quality metrics to use in practice. Moreover, they highlight issues which give rise to new directions for future research in the area of quality measurement.

Introduction

In recent times, organizations possess a tremendous amount of data concerning their customers and products. Many activities which take place in their operational processes are being recorded in event logs [28]. Techniques from the process mining field, which has grown steadily over the last decades, can be applied to gain insights in these event data [27]. In recent years, a lot of attention has been given to the discovery of process models from event logs [11], [18], [29], [35], and subsequently, the quality measurement of these models [1], [2], [6], [25], [26]. Assessing the quality of discovered models is essential in order to find out whether it constitutes an appropriate representation of the process. The quality of discovered process models has been broken down in four dimensions: fitness, precision, generalization and simplicity [22]. For each of the dimensions, several metrics have been implemented, an overview of which can be found in [32].

Although the existing metrics have been used to compare the performance of process discovery algorithms [9], little research has been done concerning the evaluation and comparison of the metrics itself. Until now, it is unclear what the differences are between metrics within the same dimension: do they judge discovered process models in a similar way, or do they qualify models differently? Are some metrics more optimistic or pessimistic than others? Furthermore, there is ongoing debate about the precise definition of certain dimensions, and the relationships between the dimensions. Nevertheless, it is essential to know which quality dimensions to take into account given a specific use case and which measures are most suitable to be used.

In this paper, we conduct an empirical study, incorporating the state-of-the-art quality metrics, with the aim to statistically analyze the relationships between metrics within and among dimensions. The results of the experiments indicate:

  • the feasibility of the metrics, in terms of CPU-time and memory,

  • whether metrics measuring the same dimension agree with each other or not,

  • whether the dimensions are related to each other, or independent from one another,

  • to which extent some metrics are more optimistic about process model quality compared to others,

  • to which extent some metrics are more sensitive to differences in process models quality compared to others.

The next section further introduces the different dimensions and the related metrics which are subject of the analysis. Section 3 discusses the experimental set up. The results of the experiment are reported and discussed in Section 4. Section 5 concludes the paper.

Section snippets

Related work

In this section, the quality dimensions are further introduced and discussed. Subsequently, an overview is given of different metrics that have been implemented. Finally, related empirical work is discussed.

Methodology

The methodology used in this paper is based on the framework for comparing process mining algorithms presented in [33]. In particular, the experiment encompasses the steps listed below. Each of these is discussed in more detail in the remainder of this section. The summary of the experiment can be found in Table 3 and a schematic overview is given in Fig. 1.1

Results

The median log size of the generated event logs was 10,704 events, with an overall minimum of 247 and a maximum of 530,203. Each log contained 3649 cases on average, while the average number of distinct activity sequences was 545. It should be noted that for the logs generated from systems with a moderate complexity, the median log size was only 5670 events, while for logs with a high complexity, this was 13,904 events.

Conclusions and future work

In the context of process discovery, being able to evaluate the quality of obtained process models as a representation of the process at hand is essential. In order to do this, different quality dimensions were introduced and for each of the dimensions several metrics were implemented. However, only limited empirical evidence exists on the behavior of these metrics and their relationships both within and across different quality dimensions. Nonetheless, the feasibility, validity and sensitivity

Acknowledgments

The computational resources and services used in this work for both process discovery and process conformance tasks were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government.

Gert Janssenswillen received the M.Sc. degree Business and Information Systems Engineering at Hasselt University, Belgium. He is currently a Ph.D. candidate at the Business Informatics research group at Hasselt University, where his focus lies in the field of business process management. In particular, his main interest goes to the quality measurement of discovered process models.

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    Gert Janssenswillen received the M.Sc. degree Business and Information Systems Engineering at Hasselt University, Belgium. He is currently a Ph.D. candidate at the Business Informatics research group at Hasselt University, where his focus lies in the field of business process management. In particular, his main interest goes to the quality measurement of discovered process models.

    Niels Donders received the M.Sc. degree Business and Information Systems Engineering at Hasselt University, Belgium. He is currently a Business Intelligence Consultant at Acumen Consulting were he focusses on enhancing business performance of its clients by streamlining processes, reducing organizational risk and leveraging the global sourcing/outsourcing organizational model.

    Toon Jouck received the M.Sc. degree Business and Information Systems Engineering at Hasselt University, Belgium. He is currently a Ph.D. candidate in the Department of Business Informatics, Hasselt University, and his current research interests include business process mining and management, data analytics and experimental design.

    Benoît Depaire is an Associate Professor at Hasselt University, Belgium. He has authored and co-authored numerous papers published in international journals and conference proceedings. His current research interests include business process management, experimental design, process simulation and IT-business models. His aim is to use gain empirically-validated insights from process-related data to understand and improve business processes.

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