Systems Thinking:Patterns

5.5 Patterns

Loop stereotypes are useful templates that help us in systems thinking. In 'The Fifth Discipline' Senge (1990) identifies a range of patterns that help us understand real-world problems. We will look at three patterns here: 'limits to success', 'fixes that fail', and 'success to the successful'.

5.5.1 Limits to success

Why don't reinforcing loops just go on increasing forever? It is because all loops will experience some limiting factor at some stage. For example, the virtuous circle in figure 5.9 may well lead to more satisfied users, but more users spending more time on the site (because they are satisfied) will also lead to more web site hits. An increase in web site hits will put more load on the server causing longer response times (especially at popular times) and the balancing loop kicks in as positive word of mouth reduces with the increase in response time. This situation arose with the UK Internet financial services provider, Egg (www.egg.com). Offers of zero-rate interest on credit card purchases for six months in January 2001 resulted in the servers being out of action as they failed to cope with the surge in demand. The capacity of the server is used as an illustration – it is just one of a number of potential limits to growth, some of which will be interdependent and therefore increase complexity. However, putting two simple loops together gives a pattern for limits to success (figure 5.10).

In figure 5.10 each of the connections is labelled with a plus or minus sign. A plus sign indicates that the two elements move in the same direction – for example, faster response times lead to increases in positive word of mouth and slower response times reduce the occurrences of positive word of mouth. The converse is the case with a minus sign – an increase in web site hits leads to slower (decreased) response times, while a reduction in web site hits leads to faster (increased) response times. The general rule is that if the number of negative connections is even (including zero) then the loop is reinforcing. If the number of negative connections is odd then the loop is balancing.

Leverage points

When the balancing loop begins to limit the growth of the reinforcing loop it is tempting to push harder, to do more of the same thing that led to the initial success: if the number of web site hits is down then spend even more money on advertising. But, the more strongly you push the levers in the reinforcing loop the more the balancing process resists. The way to gain leverage is to look for the limiting factors rather than continue to throw resources into the development of the reinforcing loop. Finding the leverage points is a key aspect of systems thinking.

When looking for leverage points, first, look for limits early – nothing can grow forever, so look for limiting factors while everything is going well. Ask the question 'what limits am I likely to encounter?' and consider how to manage growth jointly with the limits that will arrive. It may be necessary to change strategies before growth has slowed, particularly if there are delays in the system that mean growth will continue for a time while the limits work their way through.

The second leverage point comes from asking 'what is limiting growth?' Examine the limiting factor (balancing loop) and remove or weaken the constraint. For example, upgrade the server before the system crashes under peak loading and avoid the 'victim of success' syndrome. Unfortunately, dealing with one limiting factor just means further limits emerge to take its place. The fundamental lesson is that growth will eventually stop.

The third leverage point is to consider the mental models behind the actions. Continuous growth may be unsustainable or undesirable. Ask these questions:

• Is growth always a good thing?

• What will this growth get for you?

• Is there a better way to get it?

• Do you want sustainable growth?

• How far ahead are you looking for the effects?

In our web site scenario we need to at least consider these points. Is it desirable to attract more and more web site visitors? If it is, then what will the growth in visitors get us? Word of mouth is one way to increase visitors, but what other ways might it be achieved (e.g., advertising on public transport)? Do we need this growth to be sustainable or will a surge in visitors be sufficient (e.g., to satisfy the venture capitalists)? What time horizon need we plan for? Perhaps new issues and problems will arise in 6 months' time that are different in kind from those faced in the next three weeks.

5.5.2 Fixes that fail

Another common problem is the short-term fix, long-term problem. Consider the theatre box office, where bottlenecks occur in busy periods such as the pantomime season. A short-term fix might be to hire in temporary staff in busy periods. This is a balancing loop – more bottlenecks lead to more staff being brought in, and as more clerks are brought in then the bottlenecks are reduced (figure 5.11). More staff result in less space in the box office, and less box office space leads to less ticket processing efficiency, which in turn leads to more bottlenecks. The outer loop is a reinforcing loop – more staff results in more bottlenecks as box office clerks hinder each other's work. In the box office situation, hiring more staff is not the answer, unless changes to the way  the box office operates are made, such as more physical space, better layout, or possibly the introduction of an Internet ticket booking system.

5.4.3 Success to the successful

In this scenario two activities are competing for a scarce resource, such as finance or moral support. The more successful one becomes then the more support it gets – a reinforcing loop. The other activity is also subject to a reinforcing loop, but in this case it is reinforcing failure as the activity is starved of resource by the more successful activity. In the case of the theatre this pattern is illustrated by the success of alternative comedy and stand-up comedians, a form of production whose popularity at a particular point in time leads to strong demand (figure 5.12).

Good ticket sales result in more resources being made available for comedy, allowing better-known acts to be booked, reinforcing the popularity of this type of act. Dramatic productions are starved of resources and fail to book productions with big name cast members and well known directors. The fall in ticket sales for drama results in less resources being allocated, which in turn reinforces the cycle of failure. However, the theatre needs a balanced portfolio of productions if it is to survive the vagaries of fashion in the longer term. From a systems perspective the theatre should look at the overarching goal (a portfolio of production types) and balance resource allocation and achievement between comedy and drama. This pattern is typical of situations

where the coupling is unintended and leads to a climate of unhealthy competition for scarce resources.