Value stream in Lean Six Sigma

In Lean Six Sigma, a value stream is the end-to-end sequence of all actions—both value-added and non-value-added—that an organization takes to deliver a product or service to a customer. The purpose of identifying and analyzing a value stream is to improve its efficiency by eliminating waste and maximizing value for the customer. 

The concept of value

In Lean Six Sigma, "value" is defined by what the customer is willing to pay for. Any activity that does not contribute to the final product or service from the customer's perspective is considered non-value-added or waste. By distinguishing between these two types of activities, a business can streamline its processes to focus only on what truly matters to the end user. 

Value Stream Mapping (VSM)

Value stream mapping is a visual tool used to analyze and design a value stream. It is a high-level flowchart that tracks both the flow of materials and the flow of information required to deliver a product or service from beginning to end. 

A value stream map typically includes: 

• Supplier and customer: The start and end points of the process.
• Process steps: A series of boxes representing the stages of the process.
• Material and information flow: Arrows showing the movement of materials (solid lines) and information (dashed lines).
• Data boxes: Quantifiable data for each process step, such as cycle time, changeover time, and quality metrics.
• Timeline: A horizontal line at the bottom that distinguishes between value-added and non-value-added time. 

How value stream mapping is used in Lean Six Sigma

VSM is a core tool for both the Lean and Six Sigma methodologies, which focus on waste reduction and process variation, respectively. Within the Lean Six Sigma framework, it is most often used as part of the DMAIC (Define, Measure, Analyze, Improve, Control) problem-solving model. 

Example application

Consider the process of an automotive repair shop taking a car from customer drop-off to pickup.

1. Map the current state: The team draws the current value stream map, which would likely show:
   • Wait time: The car waiting in the lot for a mechanic to become available.
   • Information handoffs: A front desk employee manually writing down and transferring the repair request to the shop foreman.
   • Inventory waste: Waiting for a specific part to be delivered from a supplier.
2. Analyze the map: The team identifies non-value-added activities, such as the long wait time in the lot.
3. Design the future state: The team creates a new map that removes waste, perhaps by implementing a more efficient digital scheduling system and a better inventory management process.
4. Implement and monitor: The shop implements the new process and tracks metrics like average repair time to ensure the changes lead to continuous improvement. 

Benefits of VSM in Lean Six Sigma

• Enhances visibility: It creates a clear, visual representation of the entire process, making it easier to see how each step interacts and where waste accumulates.
• Identifies waste: VSM highlights all non-value-added activities, such as delays, overproduction, unnecessary transportation, and excess inventory.
• Improves efficiency: By focusing on value-added tasks and removing wasteful ones, organizations can streamline their operations and reduce costs.
• Encourages collaboration: The mapping process brings together all stakeholders, fostering a shared understanding and common language for improving the process.

Example: Emergency Department value stream map

Step	Current Process	Waste Identified	Future State Improvements
1. Patient Arrival	A patient walks into the ED and waits to check in at the reception desk.	Long queues at registration cause major delays.	Implement self-service check-in kiosks to reduce bottlenecks.
2. Triage	Patient waits for an available triage nurse for initial assessment.	Long waits in the waiting room for the triage nurse.	Create a "fast-track" triage for non-critical cases to speed up flow.
3. RN & MD Assessment	Patient waits in a bed for separate assessments from an RN and an MD, often with delays for lab results.	Patients wait between assessments; slow delivery of lab results.	Use an electronic health records system to give immediate access to lab results.
4. Diagnostic Testing	Patient is transported to the testing area and waits for diagnostic tests.	Unnecessary transport and long queues for diagnostic machines.	Add point-of-care testing equipment in the ED to reduce patient movement and wait time.
5. Treatment & Waiting	Patient waits for test results and the final treatment plan.	Patients occupy beds for long periods while waiting for information.	Provide real-time updates on test results to streamline communication and reduce waiting.
6. Discharge	Patient waits for discharge paperwork and final instructions.	Delays in preparing and delivering discharge paperwork.	Automate discharge paperwork and send it electronically to the patient's device.