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- 1. Health Care Workflow Process Improvement Process Mapping Lecture c This material (Comp 10 Unit 3) was developed by Duke University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number IU24OC000024. This material was updated by Normandale Community College, funded under Award Number 90WT0003. This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/
- 2. Process Mapping Learning Objectives • Create context and data flow diagrams for a health care system (or system component) using appropriate Yourdon symbols and conventions • Choose the correct scope and detail level for a process flowchart and data flow diagram 2
- 3. Process Mapping Lecture c - Topics • Yourdon data flow diagram symbols and conventions • Creating data flow diagrams (DFDs) for a given a health care scenario 3
- 4. Background • Data flow diagrams (DFDs) provide a way to document and visualize the movement of data through a process • Yourdon notation was introduced in Edward Yourdon’s 1989 book – Modern Structured Analysis • Yourdon notation exists for three types of diagrams : – Data flow diagrams – State transition diagrams – Entity-relationship diagrams • The most commonly used in health care is the data flow diagram covered in this lecture 4
- 5. Methods for Diagramming Processes Process Aspects ISO 5807 Yourdon data flow Gane- Sarson UML E-R diagram Context X X Process steps X X X Data flow steps X X X X Information content text text X X Data transformation X X X X Flow control and state X text X Roles involved X X X 5Table 3.3 Methods for Diagramming Processes. Nahm, M, 2012.
- 6. Use • The most popular use of Yourdon notation is to depict the context in which a process operates, i.e., high level interactions among o Major entities o Interactions between the process and outside entities. • Context and more detailed DFDs show – Entities – Processes (the data transformation part) – Data stores – Rather than procedural details 6
- 7. Context Diagram Example This is an example of the Context Diagram 7
- 8. Example DFD for Patient Visit 8
- 9. Yourdon Symbols These symbols are Yourdon Symbols • Dataflow diagrams consist of processes, data stores, entities, and flows 9
- 10. EntitiesEntity • Represent people, organizations, or other things that interact with an information processing system – Computerized or manual • Named with a noun or noun phrase • Send or consume information • Data flows can come to and from entities only from processes 10
- 11. ProcessProcess • Named with a single word, phrase, or simple sentence that describes what the process does: – A good name consists of a verb-object phrase o Such as assessment or assess patient • Alternatively, a name may be a person, group of people, computer, or mechanical device • It must have both inputs and outputs 11
- 12. Flow • Represented by curved arrows • Arrow heads on the flow indicate direction • Name represents the meaning of the data that moves along the flow • The same content may have a different meaning in different parts of the system 12
- 13. Data Store • Represents a collection of data at rest • Named with noun or noun phrase • Can be computerized or non-computerized, such as paper charts • Data stores are passive – Arrows to data stores mean write, update, delete – Arrows from data stores mean read, retrieve, use • Data flows to data stores can NOT come from other data stores or from entities 13
- 14. Event List • In Yourdon notation, an event list accompanies a data flow diagram • An event list contains things that stimulate action from the system • For example, for prescribing: – A patient calls for a re-fill – A pharmacy calls for a re-fill – A patient presents with a problem requiring medication 14
- 15. Conventions • Choose meaningful names for processes, flows, stores, and terminators • Number the processes by placing a unique number in the circle at the top • Redraw the DFD as many times as necessary until it is clear and complete • Simplify DFDs – A good DFD fits on one page and is not too crowded. If additional details are needed, processes can be “exploded” on a new page – Everything on one page should be at the same detail level 15
- 16. Matters of Style • Size and shape of bubbles are up to the diagram creator and their client • Curved or straight arrows can be used. Looks neater with one or the other but not both • There is no excuse for hand-drawn diagrams today except during a white-boarding stage • Some name the processes for the role that they perform • Some use color to differentiate types of entities or flows 16
- 17. Beware of • Black holes – Processes that have inputs but no outputs • Miracles – Processes that have outputs but no inputs • Mysteries – Unlabeled flows and unlabeled processes 17
- 18. Leveled Diagrams • Are encouraged • Start with higher level (context) diagrams to understand the scope and boundaries • Decompose processes to lower levels of detail when needed • Remember the ultimate goal is an optimized clinic process not a large detailed set of diagrams 18
- 19. Guidance from Yourdon “…even if our job were to ‘design the world,’ we would have to recognize that the world is only a part of the solar system, which is part of a small, obscure galaxy, which is (ultimately) part of the universe.” “…the first major model that you must develop as a systems analyst is one that does nothing more than define the interfaces between the system and the rest of the universe, that is, the environment.” -Yourdon, Just Enough Structured Analysis 19
- 20. There have been variations on Yourdon notation • Yourdon-Code • Yourdon-DeMarco • Yourdon concepts and notation have been adapted to suit needs of individual projects – Yourdon notation for data flow diagrams has been adapted for health care process analysis and redesign by the Pubic Health Informatics Institute (PHII) in their recent Common Ground Initiative – Agency for Healthcare Research and Quality (AHRQ) funded initiatives • Yourdon himself makes the point that the actual shape chosen is not important as long as the analyst uses the shape to consistently represent the same meaning 20
- 21. Example of a Modified Yourdon DFD • Modifications: • Uses one shape and does not distinguish between process, entity and data store • Calls it a context diagram • Differentiates types of flows Reprinted from Cabarrus Health Alliance http://www.cabarrushealth.org/ 21
- 22. Context Diagram Example – 2 • Without looking at the next slide, draw a one- page DFD for a prescription refill process at a primary care provider based on the following scenario: • Mrs. Jones takes Benecar 20mg QD for blood pressure control. She has taken this medicine for two years with good results. She does not use the “auto refill” program at her local pharmacy. Today, she called her provider, who does not use e-prescribing, and asked if the prescription could be called in to her pharmacy. 22
- 23. Prescription Refill Context Diagram 23
- 24. Maintenance • Yourdon notation is a set of symbols and conventions named for the person who developed it, Edward Yourdon • Yourdon notation has not been adopted as a standard – There is no formal maintenance organization • Individuals use and adapt it to suit their needs • For an adaptation to “still be” a context diagram, it must show entities, processes and interactions 24
- 25. Process Mapping Summary – Lecture c • Explain two ways process diagrams are used as models • Distinguish the physical steps from information flow in a health care process involving an EHR • Choose an appropriate process diagram to model given aspects of a process 25
- 26. Process Mapping References – Lecture c References Yourdon, E. (2006). Just Enough Structured Analysis (Rev ed.). Retrieved from Yourdon Website Charts, Tables, and Figures 3.3 Table. Nahm, M, Methods for diagramming processes, 2012. Images Slide 7: Context Diagram Example. Nahm ,M., Duke University, 2012. Slide 8: Example DFD for Patient visit. Nahm, M. Duke University, 2012. Slide 9: Yourdon Symbols or dataflow diagrams. Nahm ,M., Duke University, 2012. Slide 10: The "Entity" symbol in Yourdon notation. Nahm ,M., Duke University, 2012. Slide 11: The "Process" symbol in Yourdon notation. Nahm, M., Duke University, 2012. Slide 12: The "Flow" symbol in Yourdon notation. Nahm M., Duke University, 2012. Slide 13: "Data Store" symbol utilization in Yourdon notation. Nahm, M., Duke University, 2012. Slide 21: Diagram showing relationships of software processes in public health departments. Cabarrus Health Alliance. http://www.cabarrushealth.org/ Slide 23: Example prescription refill context diagram. Nahm, M., Duke University, 2012. 26
- 27. Process Diagrams Lecture c This material was developed by Duke University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number IU24OC000024. This material was updated by Normandale Community College, funded under Award Number 90WT0003. 27
Editor's Notes
- Welcome to Health Care Workflow Process Improvement: Process Mapping. This is Lecture c, Yourdon Notation for Data Flow Diagrams. This lecture covers Yourdon notation for data flow diagrams.
- The objectives for this lecture are: Create context and data flow diagrams for a health care system (or system component) using appropriate Yourdon symbols and conventions, Choose the correct scope and detail level for a process flowchart and data flow diagram,
- The topics covered in Lecture c are: Recognize and interpret Yourdon data flow diagram symbols and conventions, and Create data flow diagrams (DFDs) for health care scenarios.
- Data flow diagrams provide a way to document and visualize the movement of data through a process. As such, they document several aspects of processes that analysts and process designers are interested in. There are multiple notations for data flow diagrams, including ISO 5807 flowcharts, Yourdon notation and Gane-Sarson notation. We will only cover Yourdon notation for data flow diagrams lecture c. Yourdon notation was introduced in Edward Yourdon’s 1989 book Modern Structured Analysis. (Yourdon, 2006). Yourdon notation exists for three types of diagrams 1) data flow diagrams, 2) state transition diagrams, and 3) entity-relationship diagrams. (These are different from the entity-relationship diagrams that are logical relational data models covered in lecture e.) The most commonly used Yourdon diagram in health care is the data flow diagram.
- Each of the methods for diagramming a process introduced in lecture a covers certain aspects of processes. Recall that Yourdon data flow diagrams, also know as DFDs, can represent the high-level context in which a process operates, i.e., interfaces between a system and the rest of the world. Data Flow Diagrams (DFDs) can also be used to illustrate the details of entities from and to which data are received/sent, process steps, i.e., data or information transformations that occur, and data movement between entities & processes, processes and processes, and processes and data stores. Data flow diagrams do not represent information content, roles, or the logic of flow control (sequence of processes/flow can be indicated as we will see). Here we note data flow diagrams as representing data flow steps and not process steps. This is somewhat artificial; as Yourdon describes in his 2006 revision of Just Enough Structured Analysis, the data flow diagrams can be used to diagram processes. Doing so requires using flows to represent physical things such as materials or supplies and the process symbols represent operations on the materials rather than on data. (Yourdon, 2006) However, we describe DFDs as just representing data flow steps rather than process steps.
- We will cover two uses of data flow diagrams in this presentation: 1) a high-level version that is called a context diagram, and 2) more detailed versions called data flow diagrams. Both context diagrams and DFDs use the same notation, the only difference is that the context diagram is the 50,000 foot bird’s-eye view rather than the details. At the highest detail level, the context diagram represents an entire system as a single process and highlights the interfaces between the system and the outside world. Thus, context diagrams are helpful to document and share knowledge about what is included in a process (the scope).
- A context diagram (shown on the slide) is the highest level (i.e., least detail) DFD. The context diagram depicts the system or process you are modeling as one process, here private practice patient care. Entities that interact with that process are shown, here patients, payers, pharmacies, etc., as are the data stores (the EMR and an ePrescription data store), and the data flow between the entities, processes and data stores. Context diagrams are very helpful in making sure that our analysis is complete and that interactions with external entities are not forgotten.
- The example data flow diagram on this slide shows the data movement and transformations as a patient goes through the entire visit process. This begins with the reception/intake process where the intake data are entered or written to the administrative database that will be used for billing. After intake, the medical office assistant is given the room assignment. In the examination room the provider assesses the patient, charts clinical data and generates orders for further processes. The orders and clinical data are stored in the EHR. The EHR data are then used in the billing process to generate the claim for financial reimbursement (from the payer).
- Entities are origins or consumers of data (also called terminators), they are typically individuals, groups of people (for example, another department or division within the organization), external computer systems, and external organizations. Entities are referred to as “external” entities, because they are “outside” the process being analyzed, i.e., not changeable. For example in the previous diagram, the patient is not part of the receptionists intake process, but the patient’s information is an input to the process. Processes are shown by the circles, or “bubbles,” in the diagram. They represent the various individual functions or transformations that the system carries out, that is, actions or work performed on data that change them in some way, i.e., take inputs and creates different outputs (input allergies and drug order and output an allergic alert or drug-drug interaction alert). Flows are shown by curved, directional arrows. They are the connections between the processes (system functions), and they represent the information moving between processes as input and/or the information they generate as output. Yourdon refers to flows as “data in motion”. (Yourdon, 2006) Data stores represent “data at rest”. (Yourdon, 2006) They are shown by two parallel lines with a “closed end” and opposing open end. This is essentially a rectangle with one of the vertical lines missing. They show collections of data that the system must remember for a period of time. When the systems designers and programmers finish building the system, the stores will typically exist as files or databases. Yourdon published several books and papers with different people. Variations of this notation exist. We chose one here and use it consistently.
- Entities represent people, organizations, or other things that interact with the system, i.e. entities are “outside of the system”, they may, of course, be part of a larger workflow process, but they are EXTERNAL to the information system processing the data. Entities send or consume information, and are also called sources or sinks of information. Data flows can come to and from entities ONLY from processes. This is because entities are used to represent sources or consumers of information that are NOT a part of the system being analyzed; if flow between entities, for example, were represented on the diagrams, then that would imply that they were PART of the system being analyzed. As such, data flows to and from entities represent system interfaces (a very important thing to show).
- A Process should be named or described with a single word, phrase, or simple sentence that describes what the process does. A good name consists of a verb-object phrase such as assessment or assess patient. In some cases, the process will contain the name of a person, group of people, computer, or mechanical device. That is, the process sometimes describes who or what is carrying out the process, rather than describing what the process is.
- The process Flow is represented by curved arrows. Arrow heads on the flow indicate the direction of the movement of data, i.e., whether the data are moving into or out of a process or both. The name of the process represents the meaning of the data that moves along the flow. Importantly, the same content may have a different meaning in different parts of the system. For example, the address as given by a patient versus the address that has been matched and validated.
- The Data Store represents a collection of data at rest. It should be named with a noun or noun phrase, and can be computerized or non-computerized, such as paper charts. Data stores are passive, i.e., processes put data in or read data out of the data store. Arrows to data stores mean “write, update, or delete” data into the data store. Arrows from data stores mean “read, retrieve, or use” data from the data store. Data flows to data stores can not come from other data stores or from entities. As previously mentioned, a data store resembles a rectangle lacking one of the vertical lines.
- In Yourdon notation, an event list accompanies a data flow diagram. An event list contains things that stimulate action from the system. For example, for prescribing: a patient calls for a re-fill, a pharmacy calls for a re-fill, or a patient presents with a problem requiring medication.
- Yourdon notation conventions are important. The analyst should choose meaningful names for all processes, flows, stores, and terminators. Also, number the processes by placing a unique number in the circle at the top. You should redraw the DFD as many times as necessary until it is clear and complete and simplify the DFDs as much as possible. A good DFD fits on one page and is not too crowded. If additional details are needed, processes can be “exploded” on a new page. Everything on one page should be at the same detail level.
- Style matters in Yourdon notation and can be used by the analyst to provide additional meaning to DFDs. The size and shape of bubbles are up to the diagram creator and their client. Curved or straight arrows can be used. A diagram looks neater with one or the other but not both in the same process. There is no excuse for hand-drawn diagrams today except during a white-boarding stage. The analyst may choose to name the processes for the role that they perform, as well as use colors to differentiate the types of entities or flows in the diagrams. With all of these style options the DFDs can provide as much or as little detail as is needed to appropriately represent the process for the given audience.
- Beware of the following potential flaws in your process diagrams: Black holes as Yourdon calls them, are processes that have inputs but no outputs. Miracles are processes that have outputs but no inputs. Mysteries are unlabeled flows and unlabeled processes.
- We encourage the analyst to represent processes with leveled diagrams where necessary in order to have a diagram that is readily understood and can be provided at the appropriate level of detail for the audience. Start with higher level (context) diagrams to understand the scope and boundaries. These may be used for discussions with leadership in the health care setting. Then decompose the processes to lower levels of detail when needed. Remember the ultimate goal is an optimized clinic process, not a large detailed set of diagrams.
- Remember the guidance from Edward Yourdon’s 1989 work, Just Enough Structured Analysis. I quote: “…even if our job were to ‘design the world,’ we would have to recognize that the world is only a part of the solar system, which is part of a small, obscure galaxy, which is (ultimately) part of the universe.” “…the first major model that you must develop as a systems analyst is one that does nothing more than define the interfaces between the system and the rest of the universe, that is, the environment.”
- There have been several variations on Yourdon notation. Two of these are: Yourdon-Code and Yourdon-DeMarco. Yourdon concepts and notation have been adapted to suit the needs of individual projects. Yourdon notation for data flow diagrams has been adapted for health care process analysis and redesign by the Public Health Informatics Institute (PHII) in their recent Common Ground Initiative, and by the Agency for Healthcare Research and Quality (AHRQ) funded initiatives (Yourdon, 2006). Yourdon himself makes the point that the actual shape chosen is not important as long as the analyst uses the shape to consistently represent the same meaning. (Yourdon, 2006)
- Importantly, the diagram met the need for software selection and process re-design in many public health departments. The moral is, take what is useful and do not carry extra baggage.
- Without looking at the next slide, draw a one-page DFD for a prescription refill process at a primary care provider based on the following scenario: Mrs. Jones takes Benecar 20mg QD for blood pressure control. She has taken this medicine for two years with good results. She does not use the “auto refill” program at her local pharmacy. Today, she called her provider, who does not use e-prescribing, and asked if the prescription could be called in to her pharmacy.
- This example prescription refill context diagram shows the process steps and people required to refill a prescription without using a pharmacy auto-refill program or e-Prescribing through the provider.
- Yourdon notation is a set of symbols and conventions named for the person who developed it, Edward Yourdon. Yourdon notation has not been adopted as a standard. As such, there is no formal maintenance organization. Individuals use and adapt it to suit their needs. For an adaptation to “still be” a context diagram, it must show entities, processes and interactions.
- This concludes Lecture c, Process Mapping: Yourdon Notation for Data Flow Diagrams. After completion of this lecture, you should be able to: Explain two ways process diagrams are used as models, Distinguish the physical steps from information flow in a health care process involving an EHR, and Choose an appropriate process diagram to model given aspects of a process.
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