3. Materials and Methods
Figure 1 summarizes the experimental workflow adopted in this study, from event-log preprocessing and specialty-level behavioral analysis to configurable model construction, configuration-driven Process Tree derivation, and comparative evaluation.
3.2. Data Source and Experimental Population
The study used the Hospital Billing Event Log, Version 1, available through 4TU.ResearchData [
1]. The log was extracted from the financial module of the enterprise resource planning system of a regional hospital. Each case represents the administrative sequence associated with billing a package of medical services rather than the corresponding clinical treatment. The original XES file contains 100,000 cases, 451,359 events, and 18 activity labels recorded over approximately three years. Identifiers and attribute values were anonymized. Timestamps were shifted by the data provider while preserving within-case elapsed times [
1].
The 1000-case threshold was introduced as a minimum-support criterion for specialty-level behavioral representation and subsequent local Process Tree discovery. Six specialties fell below this threshold: S (743 cases; 5346 events), T (525; 2837), U (409; 2214), R (400; 2407), V (166; 1105), and W (4; 6). Together, these excluded specialties account for 2247 cases and 13,915 events. The complete specialty-level descriptive statistics are included in the supplementary reproducibility package.
To assess the influence of this minimum-support criterion, the complete preprocessing and Train-only clustering procedure was repeated from the original XES log using minimum specialty sizes of 500, 750, 1000, and 1500 cases. For each cutoff, eligible specialties were identified from the full population, the corresponding cases were subjected to a new global temporal 70/30 split, and specialty activity-set and normalized weighted-DFG representations were recomputed from Train data only. Separate configurable merges and Genetic optimizations were not repeated for each cutoff; the sensitivity analysis was designed to assess robustness of the behavioral families entering the configurable-model stage.
The case identifier, activity label, and timestamp were obtained from case:concept:name, concept:name, and time:timestamp, respectively. Event Name was used as the classifier in all ProM experiments. The source attribute speciality is recorded at the event level in the original log [
1]. Events were ordered chronologically within each case, and the first non-missing speciality value was assigned as the case-level context. Cases without a valid value were excluded. Cases containing more than one speciality value were flagged during data-quality control, and the first chronological non-missing value was retained.
The prepared log contained 23 speciality values. Specialities represented by at least 1000 cases were retained to limit instability in local process discovery. Seventeen anonymized groups, labelled A to Q, satisfied this criterion. The resulting population comprised 97,753 cases and 437,444 events. The filtered global log was defined as the union of the retained cases, and the 17 specialty sub-logs formed a mutually exclusive partition of this population.
Table 3 summarizes the fixed data and algorithm settings used throughout the experimental workflow. The retained population was divided into 68,427 Train cases and 29,326 Test cases (approximately 70/30 overall). The Train-only model-construction and held-out Test-evaluation protocol defined in
Section 3.1 was applied throughout; cluster-specific Train/Test counts are reported in
Table 4.
4. Results
The results are reported in the order of the experimental workflow. The first subsection summarizes the specialty-level grouping. The second evaluates the effect of the IMf noise threshold on the global model. The remaining subsections report the merged configurable model, the retained Genetic configurations, and the comparison between the global and context-specific models.
4.1. Specialty-Level Behavioral Grouping
Using only the Train partitions, the 17 retained medical specialties were represented through their activity sets and normalized weighted directly follows relations. Hierarchical clustering was applied to the resulting Train-only distance matrix. The selected partition separated one behavioral family, denoted Cluster K, from the remaining specialties, denoted Cluster Others. The two-cluster solution was retained because it achieved the highest mean silhouette coefficient among the candidate partitions.
The selected k = 2 behavioral-family structure was also stable with respect to the minimum specialty-size criterion. Thresholds of 500, 750, 1000, and 1500 cases retained 19, 17, 17, and 15 specialties, respectively. In every setting, k = 2 remained the silhouette-optimal partition and specialty K remained the singleton cluster. The corresponding best mean silhouette coefficients were 0.893843, 0.896026, 0.896026, and 0.891257, respectively. Thus, changing the minimum-support threshold altered specialty eligibility but did not materially change the K-versus-Others behavioral partition supplying the configurable-model stage.
Because separate configurable models were not reconstructed and re-optimized for every cutoff, this sensitivity analysis supports robustness of the cluster structure supplying the configurable stage but does not establish invariance of the resulting PTML structure or E/H/B configuration across thresholds.
The Train-only weighting sensitivity analysis showed that the clustering result was not narrowly dependent on the primary 0.30/0.70 setting. Across Jaccard weights from 0.10 to 0.90, with complementary weighted-DFG cosine weights, k = 2 remained the best partition and specialty K remained a singleton in every tested setting. The corresponding mean silhouette ranged from 0.7927 to 0.9167, while the predefined 0.30/0.70 weighting produced 0.8960. Thus, the selected K-versus-Others structure was stable across a broad range of activity-versus-routing weights rather than being an artifact of the primary weighting choice.
For the primary 0.30/0.70 Train-only analysis, the exact mean silhouette coefficients were 0.896026 for k = 2, 0.303634 for k = 3, 0.188577 for k = 4, 0.190257 for k = 5, and 0.300480 for k = 6. In the selected k = 2 solution, specialty K formed a singleton and was assigned s(K) = 0.0 under the implementation convention, whereas the remaining 16 specialties had individual silhouette values between 0.9282 and 0.9654. Thus, the high mean silhouette of the two-cluster solution was not driven by an inflated singleton score.
Figure 3 presents the Train-only hierarchical clustering structure of the 17 retained medical specialties together with the corresponding silhouette scores for candidate partitions from two to six clusters.
Table 4 summarizes the Train-derived cluster composition and reports the corresponding Train, held-out Test, and total case counts. Because the 70/30 split was global and temporal rather than stratified by specialty, the cluster-specific Train/Test proportions need not individually equal 70/30. The Test cases shown in the table did not contribute to similarity computation or cluster selection; they were assigned using the specialty-to-cluster mapping learned from Train.
Importantly, Cluster K is a singleton only at the specialty level, not at the case level. It represents 13,736 Train cases and 22,609 cases overall, so its separation is not driven by a small number of observations. Its distinct position is also consistent with the narrower activity inventory and routing structure reported in
Section 4.3. The singleton should therefore be interpreted as one specialty forming a distinct behavioral family under the selected representation, rather than as a small or unstable residual cluster.
The selected partition was also robust to the hierarchical linkage rule. Average, complete, and single linkage were applied to the same Train-only distance matrix. All three methods selected k = 2 as the best partition, with the same mean silhouette coefficient of 0.896026, and the specialty K remained the singleton cluster in every case. The alternative linkage rules produced different silhouette values for k > 2, but none yielded a partition superior to the K-versus-Others two-cluster solution. Thus, the primary clustering result was stable with respect to both the activity-routing weighting and the linkage method.
4.5. Greedy and Genetic Configuration Search
The merged configurable Process Tree was configured separately against the Cluster K and Cluster Others training logs. Both Greedy and Genetic searches operated on the same merged representation containing 20 configurable relations. The two strategies were first assessed at the configuration-output level, before the selected Genetic-derived models were evaluated on the held-out Test logs.
Greedy completed successfully as a computation, requiring 1.222 s for Cluster K and 20.701 s for Cluster Others; its exclusion was therefore not caused by a runtime error or crash. For K, the plugin reported an objective of 0.792, fitness of 0.778, and precision of 0.915. For Others, the corresponding values were 0.854, 0.848, and 0.912. However, both Greedy outputs resolved only 14 of the 20 configuration points; the returned tree structures still retained configurable elements, and the K output included one explicit null configuration value. The Greedy results were therefore excluded on the basis of a predefined configuration-completeness criterion, not because of runtime, lower downstream Test performance, or a software crash. They were incomplete configuration outputs rather than fully derived ordinary Process Trees suitable for the common downstream evaluation protocol.
Genetic resolved all 20 configuration points for both clusters. The selected K Run 2 reported a training objective of 0.985, fitness of 0.992, and precision of 0.922, while the selected Others Run 1 reported 0.912, 0.906, and 0.962, respectively. Genetic was retained because it satisfied the predefined output-completeness requirement, not because its final Test-set results were inspected in advance. Reporting the Greedy outputs alongside this criterion makes the strategy selection explicit and limits methodological selection bias.
For the Genetic strategy, five independent runs were executed for each cluster with identical parameters (fitness/precision/generalization/simplicity weights = 90/10/0/0, population size = 10, generations = 20). The configuration plugin directly returned a Derived Process Tree for each run; the fitness and precision values displayed during search were treated as optimization outputs rather than final conformance results.
For Cluster K, the five runs produced configuration-objective values from 0.978 to 0.985, fitness remained 0.992 in all runs, and precision ranged from 0.857 to 0.922. Runs 2–5 converged to the same displayed objective (0.985), fitness (0.992), and precision (0.922); Run 2 was retained according to the predefined tie-breaking rule. Runtime ranged from 8.289 s to 25.426 s. For Cluster Others, configuration-objective values ranged from 0.902 to 0.912, fitness from 0.893 to 0.906, and precision from 0.961 to 0.991. Runs 1, 2, 3, and 5 reached the same best displayed objective (0.912); Run 1 was retained because it had the highest precision among the best-objective runs (0.962, tied with Run 5) and was the earliest such run. Runtime ranged from 5 min 17.620 s to 7 min 02.847 s.
The repeated runs indicate good stability at the level of the optimized quality objective: four of five runs reached the best displayed objective for each cluster. Exact E/H/B assignments were not identical across all numerically tied solutions, indicating that more than one configuration can yield equivalent or near-equivalent objective values. Stability is therefore interpreted here in terms of convergence of configuration quality rather than exact chromosome identity. The retained configurations are reported in
Table 7, and final conformance was recalculated after Petri-net conversion using the procedure in
Section 3.8.
6. Conclusions
This study developed a configurable process mining framework that connects a hospital-wide process view with context-specific instances derived from behavioral families. Starting from 17 retained medical specialties, Train-only activity-set and weighted-DFG similarity identified two behavioral groups: specialty K and Cluster Others, with the selected k = 2 partition reaching a mean silhouette of 0.8960. In the Global Train IMf sensitivity analysis, thresholds 0.40, 0.50, and 0.60 tied on the reported conformance values (fitness = 0.8450; balanced precision = 0.9963) and aggregate structural metrics (39 nodes, depth = 11, adapted CFC = 19). An endpoint comparison of Train-derived configurable structures then fixed 0.60 as the common primary threshold because it reduced the number of configuration points from 25 to 20. A subsequent held-out 0.40/0.60 sensitivity check supported this choice without being used for threshold selection. At 0.60, the merged configurable representation contained 41 unique nodes and 20 configurable relations.
Genetic configuration search derived separate enabled, hidden, and blocked states from Train data and directly returned the corresponding Derived Process Trees. On held-out Cluster K Test cases, the Derived Process Tree achieved fitness/balanced precision of 0.9992/0.6690, compared with 0.9991/0.6245 for the directly mined K Train model and 0.6678/0.5839 for the Global Train model. On Cluster Others Test, the derived model achieved 0.8598/0.9305, compared with 0.8473/0.9312 for direct local discovery and 0.8563/0.8556 for the global model. The configurable-derived models therefore remained competitive with independently mined local models on unseen data rather than merely improving over the global reference.
The results support a complementary interpretation of classical and configurable process mining. Direct cluster-specific discovery remains a strong baseline for isolated local exploration. The configurable representation addresses an additional requirement by preserving a shared reference that makes common and variable behavior explicit and from which related cluster-specific views can be derived systematically. The contribution is therefore not to replace independent process discovery, but to connect local views to a common formal model while preserving competitive local conformance.
The operational contribution is not captured by the conformance values alone. The configurable tree separates a shared billing backbone from points at which the recorded administrative flow changes. K follows the more restricted route, while Others retains additional branches for correction, reopening, release, and status handling. For process owners, this distinction can guide where procedures are reviewed jointly and where a cluster-specific investigation is more appropriate. The anonymized labels and the administrative nature of the event log prevent a clinical explanation of these differences; the result is instead a map of divergence points that can later be combined with performance, resource, or organizational data.
The evidence is limited to one healthcare log and one configuration-search strategy retained for the final analysis. Future experiments should test other contextual attributes and datasets, vary the similarity weighting, use seed-controlled implementations where available, and extend the direct-versus-configurable baseline comparison to additional process-discovery algorithms and domains.