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Improving Improvement

A toolkit for Engineering Better Care

 

Six Sigma

The Six Sigma model is a continuous improvement approach that has a proven commercial pedigree that can be traced back to the quality revolution of the 1940’s.

Contents

 

Introduction

Six sigma is an approach to improvement developed at Motorola in the 1980s, which focuses on removing the causes of defects and reducing variation in processes. It has a meticulous focus on understanding wide-ranging customer needs, prioritising these and designing processes and systems to deliver to those needs. Its purpose is derived from the desire to achieve a performance level equivalent to a defect rate of 3.4 defects per million opportunities. Six sigma uses a disciplined and systematic approach to look at the improvement journey from a number of related perspectives: define; measure; analyse; improve; and control (DMAIC).

Six sigma is typically a facilitated process where experts use qualitative and quantitative techniques to drive process improvement. Although the tools themselves are not unique, the way they are applied and integrated as part of a system is. Six sigma professionals undergo extensive training to be able to select and use tools to evaluate a process from various perspectives and determine which activities are to be improved. It has been embraced by a number of US companies, while application in the UK health system is more limited1.

Six sigma tools help to:

  • define a problem, improvement opportunity or requirements
  • measure process performance
  • analyse processes to determine root causes of variation, defects or poor performance
  • improve process performance by addressing root causes
  • control the improved process and future performance.

The principles of six sigma are fundamentally based on a statistical approach to process control which limits unnecessary variation in performance, and it is increasingly used in conjunction with lean thinking2.

Footnotes

  1. Lessons for Lean in Healthcare from Using Six Sigma in the NHS. Proudlove, Moxham and Boaden, Public Money and Management, 28(1):27-34, 2010.
  2. Lean Six Sigma: some basic concepts. Bevan, Westwood, Crowe and O’Connor, NHS Institute for Improvement, 2013.

Getting Started

Improvement teams in health and care already have a range of theories of change and improvement approaches available: the IHI model for improvement, human factors in healthcare, lean in healthcare, experience-based co-design, root cause analysis, and six sigma to name a few.

While a number of these approaches already include tools, such as Failure Modes and Effect Analysis (FMEA) and mapping techniques that may be found in engineering methods, the systems approach presented in this toolkit has the potential to add further value to the improvement agenda in two distinct forms. The provision of new tools and ways of thinking can supplement existing approaches and the adoption of a systems approach can guide a design from a set of complex needs through to validated, effective operational systems.

There are other key areas in which new ways of thinking, derived from a systems approach, can supplement existing methods. This includes, measuring and designing system interfaces to alleviate service integration issues and using systems safety assessment to proactively design risk out of systems and avoid incidents rather than merely reactively preventing a recurrence. In such cases, existing improvement approaches may be enhanced by using techniques from a systems approach.

The Systems Approach is also a method in its own right that applies tools to answer a series of questions in an iterative and systematic way in order to guide a design from a set of complex needs through to validated, effective operational systems.

During this process, experienced improvers can use their own tools, frameworks and experiences of change to help teams understand people, deliver systems, facilitate design and manage risk. A systems approach can enhance existing approaches through additional tools and techniques, encouraging improvements to be guided by a series of critical questions or simple stage gate processes.

The following map can be used to understand the coverage of the Six Sigma model and to suggest areas where a systems approach may assist in the provision of additional questions, activities and tools to supplement existing practice.

Comparison

The questions, activities and tools from this toolkit can be mapped to the Six Sigma model of improvement to better understand the relative coverage of the two approaches. Resource material for the Six Sigma model has been analysed in detail to ascertain how it relates to the systems approach in this toolkit, both in terms of the mention of common topics and in terms of the provision of detailed descriptions or advice relating to the same topics.

Questions, activities and tools that have particular potential to add value to the Six Sigma model:

Define

The first stage of the six sigma process involves clarification of the project opportunity, creation of the team, definition of the problem aim and scope, identification of the users and stakeholders, description of measures of success, and agreement of the major milestones. Particular importance is given to the voice of users and stakeholders, and its translation to critical-to-quality (CTQ) trees which illustrate how their needs map to actionable system performance requirements, and facilitates understanding about the current processes and opportunities for improvement. Potential benefits to the users and stakeholders are also considered in the light of the resources and time required to deliver such improvement.

Activities from the systems approach, not frequently mentioned in the literature on six sigma relating to this stage, that may add value include: Observe Stakeholders, Describe Clinical Processes, Describe Patient Journeys, Create Stakeholder Map, Understand Patient Diversity, Generate Personas, Generate Scenarios, Benchmark Current Performance, Prioritise Stakeholder Needs and Agree Core Themes.

Tools from the systems approach that may be useful include: Literature Review, Soft Systems Method, Swimlane Diagram, Spaghetti Diagram, Dependency Structure Matrix, Delphi Study, Participant Observation, Observational Study, Designing Personas, Designing Scenarios, Life Café, MoSCoW, PEST(LE) Analysis, SWOT Analysis, The Five Ws and two Hs, Wardley Map, Gantt Chart, Activity Dependency Diagram and LoMo.

Measure

The second stage establishes the detailed requirements and techniques for measurement of the current system performance, in order to capture a true picture of the process. This will include the identification of measures of variance and different types of data, definition of key process input and output variables, development of a data collection plan, and an initial system analysis on data collected.

Activities from the systems approach that may add value include: Describe Clinical Processes, Describe Patient Journeys and Ensure Shared Understanding.

Tools from the systems approach that may be useful include: Causal Loop Diagram, Entity Relationship Diagram, Data Flow Diagram, State Transition Diagram, Swimlane Diagram, Spaghetti Diagram, Dependency Structure Matrix, One-to-one Interviews, Delphi Study, Participant Observation, Exclusion Audit, Expert Review, User Trials, Gantt Chart, Activity Dependency Diagram and LoMo.

Analyse

The third stage focuses on the detailed analysis of system performance data, examination of different sources of variability, determination of cause and effect relationships and root causes of problems, and identification of specific opportunities for improvement.

Activities from the systems approach that may add value include: Generate Personas, Generate Scenarios, Describe Stakeholder Experiences and Describe Patient Experiences.

Tools from the systems approach that may be useful include: Designing Personas, Designing Scenarios, Fault Tree Analysis, Hazard and Operability Analysis, Structured What-If Technique, Risk Matrix and LoMo.

Improve

The fourth stage involves creative thinking and the generation of improvement concepts that address the root causes of the variations and problems observed. These concepts are subsequently evaluated, prioritised, piloted and implemented. A future-state system process map is used to visualise the impact of the proposed changes, identify the gaps between the current and future states, and enable risk assessment of the proposed system. Cost/benefit analysis and planning for full-scale implementation are also undertaken at this stage.

Activities from the systems approach that may add value include: Analyse Relevant Documents, Describe Clinical Processes, Describe Patient Journeys, Create Stakeholder Map, Generate Personas, Generate Scenarios, Describe Stakeholder Experiences, Describe Patient Experiences, Benchmark Current Performance, Consider Pre-existing Solutions, Review Safety, Review Experience, Estimate Time Required, Present Case for Change, Identify Enablers and Blockers, Manage Team and Review Project Progress.

Tools from the systems approach that may be useful include: Literature Review, Soft Systems Method, Causal Loop Diagram, Entity Relationship Diagram, Data Flow Diagram, State Transition Diagram, Swimlane Diagram, Spaghetti Diagram, Dependency Structure Matrix, One-to-one Interviews, Delphi Study, Designing Personas, Designing Scenarios, Storyboarding, Disney, Six Thinking Hats, Morphological Chart, Exclusion Audit, Expert Review, User Trials, Fault Tree Analysis, Hazard and Operability Analysis, Structured What-if Technique, Risk Matrix, PEST(LE) Analysis, SWOT Analysis, Stakeholder Analysis, Wardley Map, Driver Diagram, Gantt Chart, Activity Dependency Diagram and LoMo.

Control

The final stage focuses on institutionalising and controlling the improved processes. This includes process monitoring, preparation of training documents, control and reaction plans, and documentation of before and after results and updated process maps.

Activities from the systems approach that may add value include: Understand Political Context, Analyse Relevant Documents, Observe Stakeholders, Describe Clinical Processes, Describe Patient Journeys, Create Stakeholder Map, Generate Personas, Generate Scenarios, Describe Stakeholder Experiences, Describe Patient Experiences, Benchmark Current Performance, Capture Stakeholder Needs, Review Safety, Review Experience and Identify Enablers and Blockers.

Tools from the systems approach that may be useful include: Literature Review, Causal Loop Diagram, Entity Relationship Diagram, Data Flow Diagram, State Transition Diagram, Swimlane Diagram, Spaghetti Diagram, One-to-one Interviews, Delphi Study, Participant Observation, Observational Study, Designing Personas, Designing Scenarios, Exclusion Audit, Expert Review, User Trials, Root Cause Analysis, Failure Mode and Effects Analysis, Fault Tree Analysis, Hazard and Operability Analysis, Structured What-if Technique, Risk Matrix, PEST(LE) Analysis, SWOT Analysis, Stakeholder Analysis, Wardley Map, Gantt Chart, Activity Dependency Diagram and LoMo.

Literature

Pande, PS, Neuman RP & Cavanagh RR (2000). The Six Sigma Way: How GE, Motorola, and Other Top Companies are Honing Their Performance. McGraw-Hill Education.

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