|
How To Use Ishikawa
Fishbone Diagram
To Determine Cause and Effect
You’ve heard
the same complaint over and over: “The problem
is we need more people!” Ok… no. The problem
isn’t that you need more people. The problem may
be that all of the mail isn’t getting delivered
by 5:00 pm. That may be a problem. One of the reasons,
or causes, or the delay in delivery is that you may
be in the midst of a hiring freeze and therefore you
don’t have as many mail carriers as you used to.
However the problem is not that you need more people.
The problem is also not that you need more money or
that you need more time. Those are not problems.
One way to find the problem to any given
situation, so that you are better equipped to find a
viable solution to the problem, is to construct a fishbone
diagram. Other names for the same graphical depiction
are called Ishikawa Diagram, Root Cause Analysis or
Cause and Effect Diagram. This tool was named after
the inventor, Kaoru Ishikawa who first used the technique
in the 1960s.
The purpose in using a fishbone is to
arrive at a handful of main causes that contribute most
significantly to the problem being examined. These causes
are then targeted for improvement. The diagram also
shows the relationships between the wide ranges of possible
contributors to the effect.
When you’re done constructing your
diagram, it will look like a fish carcass, thus the
name fishbone diagram. The problem that you’re
targeting will be in a box, or the head of the fish
to the far right of your paper. Then you’ll draw
a horizontal line cross the page. Off of the horizontal
line, you’ll draw four vertical diagonal lines
(bones) which will each represent a different main grouping
or cause category. Two will protrude on top of your
horizontal line and two will fall below the line.
Label each of the bones with the following
titles: Manpower, Materials, Machines and Methods. These
will serve as springboards for you to further delve
into each cause. For example, under Manpower –
this is where your staffing issues are listed. Perhaps
you’ll add a small horizontal bone coming off this
one that says ‘hiring freeze’ and another
bone labeled ‘training’. Continue on with
the next bone. Under Machines – you could have
“bar code sorter rejects” then “not enough
techs”.
Pretend you are a three year old and
keep asking WHY? Rule of thumb is to ask “Why?”
five times for each category. Carriers don’t return
to the office until 6pm. Why? (#1) Because we don’t
have enough to cover the routes. Why? (#2) Because some
have retired and we can’t hire more. Why? (#3)
There’s a hiring freeze. Note: Going further on
the hiring freeze may not help if that decision is beyond
your span of control. Therefore, switch gears if you
truly have no authority to change a situation. Sometimes
carriers aren’t getting back until dark because
they have to pivot and help other routes, Why? (#4)
Because the new carriers are slow. Why (#5) because
they’re not getting out of the office until 1300,
so there’s no way they can get back by 1700. Ok
stop. Now you have a definitive situation to review,
brainstorm and find a solution.
Now your problem may have just become:
New carriers aren’t leaving for the street until
1300. Then you can repeat the above process and dig
deeper until you can find the TRUE root cause. Then
fix your problem. Many times managers fix problems that
aren’t broken. Only to find their original problem
still exists.
Keep these tips in mind when creating
your Ishikawa:
1. Place the main problem you’re
trying to solve in a box on the right, for the fish’s
head.
2. This tool works alone or in team settings. Generate
and clarify all the potential sources of variation.
3. Sort your possible causes into naturally related
groups. (Use manpower, machines, materials and methods
as your guide when grouping them). The labels of these
groups are the names for the major bones on the Ishikawa
diagram.
4. Place all the causes that you’ve just brainstormed
on the appropriate bones of the diagram.
5. Ensure that the causes are specific, measurable,
and controllable. Meaning if you can’t measure
progress or defects or if you don’t have span of
control to do something about it, select another cause
that you can actively work to rectify.
As you find solutions to little problems,
continually rework your diagram. You’ll be amazed
at the small incremental steps you’ll make at improving
your overall operations. This visual depiction of the
problems will help you stay focused on true root causes
and solutions. No longer will you operate off complaints
such as “The problem is we don’t have enough
people!”
1howto.com
--------------------------------------------------
Please
Share Your Tips with Us
|
