Video Transcript: Cause & Effect Diagrams

Bob Lloyd, PhD, Executive Director Performance Improvement, Institute for Healthcare Improvement

One of the basic tools of quality improvement is the cause and effect diagram. This is also known as the fish bone diagram, for obvious reasons, since the spines of the cause and effect diagram, with the terminus, make it look like the skeletal system of a fish. These are also classically known as Ishikawas, named after Dr. Akira Ishikawa, who was one of the first to use these, a quality expert from Japan. Usually, you put the problem or the issue that you’re interested in, in the box to the right. Then, the spines get labeled with categories, and we’ll talk about these in a moment. Typically there’s about four or five depending on the nature of the issue. Now I must also say that the problem, or issue, is typically something that you would want to investigate, an adverse event, an error. Typically, these are done in conjunction with a root-cause-analysis. Matter of fact, there are times when organizations have to actually submit a cause and effect diagram to document how they’ve investigated an issue, and event, an adverse event, or an error.

So let’s think about the major categories that people actually put into these boxes. The classic ones are in terms of machines, methods used, materials involved, and finally people. So you would put people, materials, methods, etc. in each box. Other categories that people have used however, include equipment, or space, which can often times add to an issue, policies, procedures, people, environment again, and finally measurement. My point in bringing all of these out is that the categories you put in these boxes really depend on the nature of the issue. Other times people also put functions in here. Let’s think about medication orders. So, you have prescribing, you have filling in the pharmacy of the order, you have dispensing back to the unit, and finally you have administering the med to the patient. So, you could envision putting functions up in these boxes. Often times when you use this grouping, or this, you’re dealing with nouns and things, but often times in health care functions work, prescribing, filling, dispensing, and administering.

So let’s take a quick look at what one of these would look like as you break out a category. We have our fish bone, and we have our spines. What I’m going to do is look at one of these, the people. If we were looking at a medication error that occurred, and we say, “Who are the people involved?”, at this point we might have one line coming off the main spine of the people and say there was the Doctor who wrote the order, then there was the Nurse who took the order, gave it to a Nurse Assistant who sent it to the Pharmacy, so now you have the Pharmacy Tech, who receives it from the Nurse, or the Nursing Assistant, you have the Director of Pharmacy who might be involved, and finally consider that you might even have the patient involved. Patients often times check their medicine, or if the patient is not doing too well and can’t speak for him-or-herself, then the family might be involved. So as you start laying out the details of any one of these categories you start to have these branches. So you’d have the main line and then you have a single branch for one person, and in this case we have two people, you could go down further if there was yet another person. So the detail, and the level of detail, is dependent on you and the complexity of the issue, but the cause and effect diagram is a classic tool, and one of the ones that you should have in your toolkit as you pursue your quality improvement programs.