# CONDA-PM--A Systematic Review and Framework for Concept Drift Analysis in Process Mining
## 4 Research Methodology
### Research Questions  
The aim of the SLR is to gain an in-depth understanding of the solutions proposed by current approaches to concept drift analysis in the context of process mining. We are concerned with reviewing studies on concept drift analysis in order to derive characteristic properties of corresponding analysis approaches in terms of inputs, processing, and outputs. These properties are used afterwards for developing an understanding of what constitutes a comprehensive approach to concept drift analysis in process mining. This understanding, in turn, provides the basis for deriving the CONDA-PM framework we introduce in Section 6. In detail, the SLR investigates the following research questions:  
1. RQs investigating the inputs of an approach: * _RQ1: What are the inputs needed by a concept drift analysis approach?_--This question targets identifying the artefacts used by an approach as starting point for concept drift analysis. This kind of input affects the choice of the techniques to be used at the presence of this input, the expected outcome, and the kind of change to be studied, that is, whether the approach is concerned with analysing behavioural or structural process change. 2. RQs investigating the processing phase of an approach: * _RQ2: How can concept drift analysis be classified to gain a more profound understanding of the characteristics of the various approaches?_--Trying to find some matching criteria between approaches may help in gaining understanding of the potential building blocks of a concept drift approach, and hence, enabling forming this understanding into a guiding framework. Finding and exploring differences between contemporary approaches may help in identifying specific application scenarios for these approaches. * _RQ3: Which process perspectives are subject of concept drift analysis processes?_--This research question studies which perspectives of an event log are covered an existing approach, which is crucial to judge the expressiveness of the approach. For example, the control-flow perspective may be used to study both structural and behavioural changes of a business process, whereas studying changes concerning the time perspective can facilitate the task of predictive monitoring, enriching it with information beneficial for performance-related predictions. * _RQ4: Which granularity level of a business process is mainly addressed by existing concept drift analysis approaches?_--Studying the granularity level of a change (i.e., whether the change is applied at the process type or process instance level) is crucial to derive insights on the prevalence and effects of the change. A drift on the process type affects the related process variants, and hence, a larger number of process instances than a drift on the instance level which is limited to one single variant of this business process. Identifying the level at which a change occurs is important in making a decision on how to handle the change and in calculating the costs of making corrective actions or propagating the change. 3. RQs investigating the outputs and evaluation of an approach: * _RQ5: Do existing approaches provide usable implementations_?--The maturity of any approach is reflected by the availability of a technical implementation, being able to demonstrate its applicability and sustainability. * _RQ6: How does an approach to concept drift analysis foster a business process proactivity to change?_--Studying a concept drift in an online setting has different implications than studying it in an offline mode. Furthermore, the ability of an approach to precisely define both the moment and type of drift is crucial for guiding the decision making process. Yielding precise outcomes of a concept drift analysis approach affects related procedures, for example, predicting the outcome of a process instance when knowing that this process instance was subject to a drift during its execution.