Examples of Tools for Root Cause Analysis
There are many different techniques available to conduct root cause analysis. Two of the easiest to use are the 5 whys and a cause-and-effect diagram.
The 5 Whys
The 5 whys simply asks the user of the technique to question why a certain condition occurs and to continue to question why each underlying condition given as an answer to the preceding “why?” occurs until the questioning reaches a point where there is no other underlying condition left – this is the point at which the root cause has been discovered. The technique is called the 5 whys because the rule of thumb is that it generally takes five iterations of asking why? until a root cause is reached. Below is an example of the 5 whys used in a school district where the problem is lower-than-expected performance on a reading program. The example shows how this technique can lead to branching inquiries.
The 5 whys has the advantage of being easy to use, but may lead the user to overlook different possible branches of inquiry into root causes in favor a single branch of inquiry. The next technique, cause-and-effect diagrams, overcomes this weakness.
A cause-and-effect diagram is also known as an “Ishikawa diagram” (after its inventor) or a “fish-bone diagram” (after its appearance). A cause-and-effect diagram places the problem to be analyzed on the right of the diagram and then draws multiple branches of potential causes from the initial problem. The major branches of inquiry coming off of the immediate problem usually represent major categories of potential causes that the user of the diagram investigates. Sub-branches may be added to the major branches to show deeper underlying causes. Exhibit 1 illustrates.
Exhibit 1 – Cause-and-Effect Diagram
To perform a root cause analysis, start with the problem and then identify potential causes and sub-causes. Standard categories of causes are often used in order to provide the user with guidance on where to look. The standard categories used in manufacturing and service industries may not be optimal for school districts, so the standard categories of root causes for school districts that were described earlier in this document could be integrated into a cause-and-effect diagram to create a template (see Exhibit 2).
Whether using pre-defined categories or not, a root cause analysis should be guided by data and investigation. Sources of information to guide the search for root causes include test data and other student performance assessments, surveys of stakeholders, and interviews with people who work closely with the issue in question.
Exhibit 2 – Cause and Effect Diagram with the School Categories
Exhibit 2 provides an example of a template completed by Traverse City Area Public Schools (TCAPS), Michigan for the problem that not all students read at grade level. The diagram shows how TCAPS investigated a variety of causes behind the problem. TCAPS used data from a number of published research studies to aid their analysis. For example, what are the most effective pedagogical methods in the classroom and is TCAPS following them? What are the successful habits of student learning and is TCAPS helping students to learn those habits?