Causal Pathway Diagrams

Toolkit for selecting, designing, tailoring, and optimizing implementation strategies

Who is this toolkit for? 

This toolkit is designed for researchers with a background in implementation science. It is intended to support those who are developing, testing, or using implementation strategies to improve health care.

While this tool is also applicable to implementation practitioners, such as quality improvement teams, this version of the toolkit is geared towards scientists who are conducting implementation research. Future iterations will incorporate a process adapted for implementation practitioners. 

Getting Started

What is a causal pathway diagram? 

Causal pathway diagrams (CPDs) are a tool to help implementation scientists to develop, select, optimize, and evaluate implementation strategies, with a deliberate focus on context. They are graphical representations of the processes that connect implementation strategies with the outcomes they are intended to impact (see Figure 1, below). 

CPDs guide users to clarify their assumptions about

  • How implementation strategies work
  • The circumstances  under which they work
  • How they work in combination with other implementation strategies

Those assumptions can be vetted and tested to ensure users are prioritizing strategies that are most likely to be effective. CPDs are a tool intended to aid the field’s efforts to move beyond an “it sounded like a good idea at the time (ISLAGIATT)” approach to a precise and targeted approach to support implementation.  



Figure 1. Example structure of a causal pathway diagram. Instructions for use of the causal pathway diagram and explanations of the elements are included in this toolkit.

Why use causal pathway diagrams? 

Implementation strategies do not directly impact health outcomes. Instead, they initiate a chain of events—such as organizational changes and changes in social norms—that can affect whether, how well, and for how long evidence-based interventions (EBIs) are used. Their ultimate success depends on the successful activation of each event in this chain. The complexity of implementation, and the interaction of strategies and local conditions, has historically led to low rates of implementation success.

We believe that a key reason for limited implementation success is that implementation initiatives do not pay sufficient attention to the process—the full chain of events—that connects implementation strategies to the intended implementation outcomes. CPDs provide a structure to think carefully about how implementation strategies will work best. CPDs have six core functions:

  1. Selecting or designing an implementation strategy
  2. Understanding the conditions under which an implementation strategy will work
  3. Designing and optimizing multifaceted implementation strategies
  4. Developing causal theories of how implementation strategies work
  5. Measuring implementation strategy functioning
  6. Diagnosing why an implementation strategy did not work as intended


When to use causal pathway diagrams

We encourage the use of CPDs throughout the implementation process. They can be useful while planning and during implementation and after implementation is complete.    

  1. Planning for implementation: To guide you through selection and design of an effective implementation strategy 
  2. During implementation: To inform the evaluation of an active implementation strategy and guide adaptive approaches to increasing effectiveness 
  3. After implementation: To clarify why a strategy did or did not work as planned 


How to use this toolkit

This toolkit is a one-stop shop for nearly everything you need to know about using CPDs. Instead of reading from beginning to end, navigate to the most relevant sections.

Section 1: An Introduction to Causal Pathway Diagrams

This section is the starting place if you are interested in learning about CPDs. It describes the structure of a CPD and introduces its elements.

Section 2: Principles and Practice of Developing Causal Pathway Diagrams

This section is for a deeper understanding of the process for developing a CPD, each element that makes up a diagram, and principles for their development.

Section 3: Functions of Causal Pathway Diagrams

This section provides in-depth guidance and examples illustrating how to develop a CPD for six different functions. You may find it most helpful to navigate to specific CPD functions of interest.

Frequently Asked Questions

This section addresses common questions that come up while developing a CPD. It is most useful if you have a basic understanding of CPDs and want guidance on more complex issues, such as how to operationalize and implementation strategy or how to select and define a mechanism.

Tools to Build Your Own Causal Pathway Diagram and Additional Resources

A separate document includes tools for developing a CPD such as a diagram template and questions to guide the CPD development process. It also has a section with links to resources on implementation science topics that may be helpful as you develop a CPD. The resources include implementation strategy compilations to identify possible strategies and links for identifying and prioritizing determinants.

Thank you for downloading the toolkit. We would like to understand more about who is using these methods and how they are being used.

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Funding acknowledgment

Funding for this toolkit comes from the National Institute of Mental Health (P50MH126219) and  the National Cancer Institute (P50CA244432, R01CA262325).