A guide to help with the creation of a Pareto chart.

1. © ABCi 2019
What is a Pareto Chart?
Where each of the causes to a particular problem
are able to be quantified, a pareto chart presents
these in descending order so that you may highlight
those causes that contribute most to a problem. A
pareto chart helps you to focus your attention on
the causes/issues that have the greatest potential
for improvement.
What are the benefits of using this technique?
Pareto analysis will help you to identify those causes that contribute most to a problem, enabling you
to work on an area that has the greatest potential for improvement, often called the ‘low hanging fruit’.
When would you use this technique?
This method can be useful after carrying out a ‘cause and effect’ or Fishbone analysis. However you
may only use it when you are able to quantify the contribution of each of the causes of a problem.
These may be different causal reasons or different sources e.g. wards or clinics, where a process failed.
How do you do it?
Step 1: Once you have identified the causes of
your problem, collect data, e.g.. count the
number of times something has caused your
problem – see table right.
Make sure that you choose the best unit of
measurement that relates to your problem
(usually it will be frequency or cost). For example,
causes for lost outpatient appointment.
What resources do I need?
• Data quantifying contribution to a problem
• Pen and Paper / Microsoft Excel
Step 2: Rank this data from largest to smallest -
see table right.
Pareto ChartABC
improvement
iSkills for
The Pareto Principle or 80/20 rule was originally coined by Vilfredo Pareto, he realised that 80% of
the land in Italy was owned by 20% of the population. Whilst the exact numbers may change, this
concept is useful for improvement. If 80% of your problem is derived from 20% of your cause, this is
where you could focus your initial efforts to get the ‘biggest bang for your buck’.

2. © ABCi 2019
Step 3: This data then needs to be
represented as a percentage of the total.
For example 703/1197 x 100 = 59%
- see right.
Step 5: Now a Pareto chart can be created in order to illustrate your findings. Problem causes/sources
will be plotted on the horizontal axis and frequency/cost will be on the vertical axis. Constructing a
column chart, where the contribution of each problem cause is ranked in descending order forms the
basis of a pareto chart (see below). Immediately you can see where the largest problem lies i.e. Patient
DNA. Adding another axis (right of chart), representing the cumulative frequency, enables you to
assess the contribution of each cause. For instance ‘Patient DNA’ constitutes around 60% of the
number of lost appointments.
If you follow the dotted line from 80% to where this cuts through the cumulative percentage line, and
then down. Anything to the left of this line represents 80% of your problem, ‘the vital few’. Focussing
your improvement efforts here will achieve higher gains.
Step 4: A cumulative percentage of each category is then calculated. To do this
leave the top category as it is (in this example 59%) and then add on each category’s percentage down
the list. For example 59% + 21% = 80%, 80% + 11% = 91%, 91% + 7% = 97% (rounded down) etc. The
cumulative percentage will always add up to 100% - see below.