Root cause analysis: the fishbone diagramme


The fishbone diagram is a cause-and-effect diagram that can be used  to  identify  the  potential  (or  actual)   cause(s)  for  a performance  problem.  Fishbone  diagrams  provide  a  structure  for  a  group’s  discussion  around   the  potential  causes  of the problem.

Needs assessment applications

Fishbone diagrams are often used in needs assessment to assist in illustrating and/or communicating the relationships among several potential (or actual) causes of a performance problem.  Likewise, these graphical representations of relationships between needs (i.e., discrepancies between desired and actual results) offer you a pragmatic tool for building a system of performance improvement interventions (for instance, a combination of mentoring, job aids, training, motivation, new expectations) around the often complex relationships found across potential (or actual) causes.

Advantages and disadvantages


  • Fishbone  diagrams  permit  a  thoughtful  analysis  that  avoids  overlooking  any  possible  root  causes  for  a need.
  • The  fishbone  technique  is  easy  to  implement  and  creates  an  easy-to-understand  visual  representation  of the  causes,  categories  of  causes,  and  the  need.
  • By  using  a  fishbone  diagram,  you  are  able  to  focus  the  group  on  the  “big  picture”  as  to  possible  causes or  factors  influencing  the  problem/need.
  • Even  after  the  need  has  been  addressed,  the  fishbone  diagram  shows  areas  of  weakness  that  – once exposed  –  can  be  rectified  before  causing  more  sustained  difficulties.


  • The  simplicity  of  a  fishbone  diagram  can  be  both  its  strength  and  its  weakness.  As  a  weakness,  the   simplicity  of the  fishbone  diagram  may  make  it  difficult  to  represent  the  truly  interrelated  nature  of   problems  and  causes  in  some very  complex  situations.
  • Unless  you  have  an  extremely  large  space  on  which  to  draw  and  develop  the  fishbone  diagram,  you may  find  that  you  are  not  able  to  explore  the  cause  and  effect  relationships  in  as  much  detail  as  you would  like  to.

How to use the tool

  1. Identify  gaps  between  the  results  (i.e.,  performance)  that  are  required  for  the  successful  accomplishment of your  programs/projects  results  chain  (i.e.,  logic  frame)  and  current  achievements  to-date.
  2. Generate  a  clear,  concise  statement  of  the  need(s).  Make  sure  that  everyone  in  the  group  agrees  with  the need as  it  is  stated.  For  example,  the  national  administration  has  been  able  to  provide  reports  on  time   in  respect  of (on average) 25% of reports actually requested during the last 10 years and the aim of your  program/project  is  for  100% of  the  reports requested each reporting year to be provided on time, with informative and responsive content.
  3. Using  a  long  sheet  of  paper, draw a line horizontally along the page.  This line will be the “spine” of the fish. Write  the  need  along  the  spine,  on  the left hand side.
  4. Identify  the overarching categories of causes of the need. Brainstorming is often an effective technique for identifying  the  categories of causes.  For each category of causes, draw a “bone”, a line at a 45 degree angle from the spine of the fish. Label  each  spine  (see  Figure  1).
  5. Have the group brainstorm to identify the factors that may be affecting the cause and/or the need.  For each category of causes, the group should be asking:  “Why is this happening”?  Add each “reason why” to the diagram, clustered around the major cause category it influences.
  6. Repeat the procedure for  asking “Why  is  this  happening” for each effect, until the question yields no more meaningful  answers (see  Figure  2).
  7. When the group has come to the consensus that the diagram contains an adequate amount of information, analyze the  diagram.  In particular, look for causes that are appearing in more than one section of the diagram.
  8. Circle anything that seems to be a root cause for the need.  Prioritize the root causes and decide to take action. This action may involve further investigating the root causes.





Tips for success

  • Make sure that there is consensus in the group about both the “need” and the characteristics of the “cause statement”  before  beginning the process of building the fishbone diagram.
  • If appropriate, you can “graft” branches that do not contain a lot of information onto other branches.   Likewise, you can “split” branches that have too much information into two or more branches as you go.
  • Make parsimonious use of words while populating the fishbone diagram.  Only use as many words as
    necessary to describe the cause or effect.

References and resources

  • This tool is adapted from a WBI Evaluation Group tool, first published in 2007.
  • Gupta,  K.,  Sleezer,  C.M.,  &  Russ-Eft,  D.F.  (2007):  A  Practical  Guide  to  Needs  Assessment, Pfeiffer.
  • The  Fishbone  Diagram (from  Six  Sigma;  has  templates  for  making  fishbone  diagrams  in  Microsoft  Word  and  Microsoft  Excel).