---
title: Conformance Checking
type: concept
tags: [bpm, process-mining, conformance, monitoring, compliance]
sources: ["[[sources/2011-vanderaalst-process-mining-book]]", "[[sources/2018-dumas-fundamentals-of-bpm]]", "[[sources/2012-vanderaalst-process-mining-manifesto]]"]
created: 2026-04-20
updated: 2026-04-20
---

# Conformance Checking

The second of the three pillars of process mining: given an event log **and** a process model, quantify and localise deviations ([[sources/2011-vanderaalst-process-mining-book]], Ch. 8). Distinguished from **discovery** (log → model) and **enhancement** (log + model → improved model).

## Three techniques

1. **Token replay** (§8.2) — push each trace through the model; count missing/remaining tokens. Simple, but gives coarse diagnostics on non-fitting traces.
2. **Alignments** (§8.3) — compute a cost-optimal synchronous product between trace and model (log moves / model moves / synchronous moves). Dominant technique since the late 2000s; produces interpretable step-by-step deviation diagnostics. Introduced to the textbook in the 2nd edition.
3. **Footprint comparison** (§8.4) — compare direct-succession matrices of log vs model; cell-level disagreements reveal structural mismatches. Fast but log-model-symmetric (no trace-level diagnostics).

## Four quality dimensions

Conformance is scored along four dimensions ([[sources/2011-vanderaalst-process-mining-book]], §6.4.3; echoed in [[sources/2018-dumas-fundamentals-of-bpm]] §11.4.4):

- **Fitness** — can the model replay the traces in the log?
- **Precision** — does the model *only* allow behaviour seen in the log, or does it over-generalise?
- **Generalisation** — will the model handle unseen-but-plausible future behaviour?
- **Simplicity** — Occam: is the model the smallest adequate explanation?

These trade off against each other; the four-way tension is the conformance equivalent of the [[concepts/devils-quadrangle|Devil's Quadrangle]] in redesign.

## Applications (§8.5)

- **Compliance auditing** — check four-eyes principles, segregation of duties, SOX/GDPR rules.
- **Model repair** — patch the model where it disagrees with observed reality.
- **Discovery algorithm evaluation** — use alignment-based fitness/precision as benchmark metrics.
- **Model-to-log linkage** — annotate log events with their model position for downstream analysis.

## Two viewpoints on deviations

Per [[sources/2011-vanderaalst-process-mining-book]] §2.3:
- **Descriptive model** (the model is wrong): deviations reveal model error; fix the model.
- **Normative model** (reality is wrong): deviations reveal non-compliance; fix the process or the people.

The same alignment produces different actions depending on which viewpoint is adopted.

## Related
[[methods/process-mining-basics]] · [[concepts/process-discovery]] · [[concepts/process-model-quality]] · [[concepts/operational-support]] · [[frameworks/declare]] (declarative conformance via LTL replay) · [[entities/wil-van-der-aalst]]

## Out-of-scope
Not to be confused with **Statistical Process Control** (SPC — control charts over numerical measurements, see [[sources/2007-slack-operations-management]] Ch. 17) or **chemical-engineering process control** ([[sources/2007-bao-lee-process-control-passivity]]). These are three distinct traditions that share the word "control".