Also called: systematic diagram, tree analysis, analytical tree, hierarchy diagram
The tree diagram starts with one item that branches into two or more, each of which branch into two or more, and so on. It looks like a tree, with trunk and multiple branches.
It is used to break down broad categories into finer and finer levels of detail. Developing the tree diagram helps you move your thinking step by step from generalities to specifics.
Brainstorm all possible answers. If an affinity diagram or relationship diagram has been done previously, ideas may be taken from there. Write each idea in a line below (for a vertical tree) or to the right of (for a horizontal tree) the first statement. Show links between the tiers with arrows.
The Pearl River, NY School District, a 2001 recipient of the Malcolm Baldrige National Quality Award, uses a tree diagram to communicate how district-wide goals are translated into sub-goals and individual projects. They call this connected approach “The Golden Thread.”
The district has three fundamental goals. The first, to improve academic performance, is partly shown in the figure below. District leaders have identified two strategic objectives that, when accomplished, will lead to improved academic performance: academic achievement and college admissions.
Tree Diagram Example
Lag indicators are long-term and results–oriented. The lag indicator for academic achievement is Regents’ diploma rate: the percent of students receiving a state diploma by passing eight Regents’ exams.
Lead indicators are short-term and process-oriented. Starting in 2000, the lead indicator for the Regents’ diploma rate was performance on new fourth and eighth grade state tests.
Finally, annual projects are defined, based on cause–and–effect analysis, that will improve performance. In 2000–2001, four projects were accomplished to improve academic achievement. Thus this tree diagram is an interlocking series of goals and indicators, tracing the causes of systemwide academic performance first through high school diploma rates, then through lower grade performance, and back to specific improvement projects.
Excerpted from Nancy R. Tague’s The Quality Toolbox, Second Edition, ASQ Quality Press, 2004, pages 501–504.