System Flow

System flow is about improving people’s experience of moving through a series of services, or the movement of work through a series of processes.

What do we mean by system flow?

Often in our public services we are concerned with improving the movement of people through a series of services or steps. For example, through a health & social care pathway, or through the justice system. We might also be concerned with the flow of work (e.g. application forms or information requests) through a process. There are some specific tools and concepts that are useful for understanding flow.

Understanding system flow

When seeking to improve flow, the following steps can help you understand where to start looking for change ideas to test.

1. Map out the entire process as it really works (not as the imagined or ideal state), involving staff who work in it, and service users where you are looking at a user journey. This might potentially be across different organisations or departments, so think about who to involve.Identify any unnecessary steps or work that isn’t benefitting the service users and look at how to stop doing it. Gather insights from staff and service users to identify any quality issues that could be addressed to make sure things get done right first time. Look at data on how long the overall process takes as well as each step within it, and the variation in these times.

2. Identify bottlenecks in the process.  Every system has a ‘rate-limiting step’. This is the step that determines the rate at which work passes through the whole system.  To find it, observe where the work is piling up, or where the longest queues are forming.  Map out the step in detail, and identify the constraint that is causing the bottleneck (e.g. specific skills, equipment, space).  It may be useful to use a tool like the 5 whys to get to the underlying reasons for the bottleneck.  Focus improvement on making best use of capacity at the rate-limiting step.  Capacity can potentially be optimised by improving how skill mix is used and how work is organised.

3. Analyse data on demand, capacity, activity and queues.

Demand is all the work that needs to be done

Capacity is how much work could be done considering all of the resources needed

Activity is the actual work done, it is the throughput of the system

Queue is the work that has not been done – the backlog or waiting list

It is important to understand the variation in your system, so plot your data over time on run or SPC charts. Depending on the system it may be appropriate to look at data hourly, daily, weekly or monthly.

Consider how to properly understand and plan for the true demand on the system, and work to reduce the demand that is generated by the system.The system creates demand by failing to get things right the first time, by including unnecessary steps and crucially by failing to understand what people really need and want. In health and social care the principles of Realistic medicine should be adopted.

When analysing capacity it’s important to look at actual capacity – using activity data as a proxy for how much work you could do can be misleading. This means understanding how much time people can actually spend on the required tasks. The capacity calculator tool can help you get started with this.  Availability of resources such as rooms and equipment also need to be considered.

Often queues are caused by a mismatch between capacity and demand so explore this before assuming you need additional capacity.There may be potential to better plan capacity to meet predicted demand. Note that while you need to maximise capacity use at the bottleneck it won’t be possible to do this across the whole system.

Pooling queues and reducing batching can reduce overall process time. Look at whether the design of the system is creating additional demand and activity and what could perhaps be done differently.

Tools to help you understand system flow

Process Mapping – Used to outline the sequential steps in a process.

Run Charts - A line graph of data plotted over time.

SPC Charts - A simple graphical tool that enables process performance monitoring.  

5 Whys -  Used to identify underlying reasons for a problem.

Capacity Calculator - Used to understand the capacity of your team members and time spent on tasks.

Further reading to understand system flow

NHS England have created some helpful guides providing more detail:

Mapping the process

Theory of constraints 

Demand and capacity overview 

Guide to improving flow (Seven Ways to No Delays)