Strategy Survival Guide

The diagrams help to improve understanding of the drivers of behaviour in the system, and can uncover
counter-intuitive effects of interventions. They can show how a change in one factor may have an impact
elsewhere or feed back to affect itself, and also how two seemingly independent factors are actually linked.
Influence diagrams are best constructed in a working session with a small number of key people. The
sessions are likely to stimulate in depth discussion as each participant’s assumptions and views are explored
and incorporated into the emerging picture.
Driver Trees
An influence diagram aims to map the relationship between all the variables in a system. However, it is likely
that there are one or two key variables of particular strategic interest that need to be either maximised or
minimised. Unravelling the influence diagram into a driver tree can be a powerful way of highlighting and
communicating the drivers of these key variables, and hence provide insight into the kind of interventions
that are needed to impact them.
Unravelling the influence diagram above can help to highlight the drivers of cost. The feedback loops in the
system mean that certain variables appear in more than one branch of the tree. Where variables are
repeated in this way they are conventionally placed in brackets.
Training
+
Morale
-
Staff turnover
+
Recruitment
+
(Recruitment)
+
Training
+
Costs
Driver trees raise a number of questions, not least the relative significance of the different branches of the
tree in driving the key variable.
Impact Trees
There will be only a limited number of variables within a system that can be directly influenced to act as
levers for change. An alternative way to unravel the influence diagram is to highlight the impact that
managing these variables will have on the rest of the system. Again using the example influence diagram
above, an impact tree can be constructed to more explicitly highlight the consequences of increasing the
level of training as described above.
+
Costs
Training
+
-
Morale Staff turnover
+
Recruitment
+
Costs
Impact trees provide a causal sequence for understanding how managing one variable is expected to have
an impact on another variable of interest. Social Researchers encourage a similarly explicit articulation of
how an intervention is expected to have its impact using Theories of Change methodology, outlined in the
Magenta Book.
Interpreting Feedback Loops
Constructing an influence diagram will highlight the great number of feedback loops that exist within any
complex system. Interpreting these loops is central to understanding the likely behaviour of the system.
Strategy Survival Guide – Strategy Skills
Page 97