A fishbone chart (フィッシュボーンチャート) is another name for a cause-and-effect diagram (特性要因図). It arranges a problem result and the causes that produce it in a shape like a fish skeleton.
The result (the characteristic) goes in the fish head at the right end, and large and small bones branch off the spine leading to it, each holding a cause. The large bones carry broad cause categories, and splitting them by angles such as people, equipment, materials and methods makes gaps easier to notice. Causes get more specific toward the small bones, which helps you trace the root cause.
AnalogyIf dinner gets burnt, writing out the reasons under bones for heat, cookware, ingredients and steps keeps you from jumping to one cause on a hunch.
How to rememberThe name simply joins the English words fish and bone.
Exam points
ExamFishbone chart (フィッシュボーンチャート) and cause-and-effect diagram (特性要因図) are two names for one diagram. It lays out the factors behind a result along the bones and is used to pin down the underlying cause.
Mix-upSetting priorities by tackling the most frequent causes first is what a Pareto chart (パレート図) is for. A cause-and-effect diagram lines up candidate causes along its bones, so the two play different roles.
A control chart (管理図) plots measurements in order as a line and draws a center line plus upper and lower control limits, to judge whether a process is in a stable state.
Measure each sample
Set the center line and control limits
Plot values in order
Check points outside limits and runs
Treat points beyond the limits, or points that keep falling on one side, as warning signs and look for the cause.
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The horizontal axis shows time order or sample number, the vertical axis shows the quality value, and a center line (CL) marks the average. While the points scatter irregularly between the upper control limit (UCL) and the lower control limit (LCL), the variation is treated as chance and the process is judged stable. A point beyond a limit, or a run of points on one side of the center line, signals a cause that chance can hardly explain, so it gets investigated.
AnalogyLog your morning commute every day and mark the usual range with an upper and a lower line. When a day falls outside that range, check whether there was an accident or roadwork.
How to rememberThe three lines are CL, UCL and LCL: CL stands for Center Line, and UCL and LCL for Upper and Lower Control Limit.
Exam points
ExamA control chart (管理図) uses the upper and lower control limits as the benchmark and flags any value that goes beyond them as abnormal.
Mix-upA Pareto chart (パレート図) combines bars sorted from the largest count down with a line of cumulative percentages. ABC analysis (ABC分析) also uses this chart. A Pareto chart has no control limits.
Mix-upA scatter diagram (散布図) shows how two quantities relate through the spread of points, and a histogram (ヒストグラム) shows the frequency of each interval as bars. Neither one judges abnormality against limit lines.
A tree diagram (系統図) breaks an objective you want to reach into the means that achieve it, then splits each means into finer means, branching level by level.
Shorten meetings
Prepare in advance
Send materials the day before
Set a time limit per agenda item
Invite fewer people
Invite mainly decision-makers
Share minutes with those absent
Treat each first-level means as an objective and break it into more concrete second-level means.
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A means at one level is the objective for the level below, so asking "how do we do that?" again and again keeps the branches growing. You stop when the branch tips become concrete actions that can be assigned an owner and a deadline and started. The result lists every measure that could serve the objective and gives you material for deciding which to carry out first.
AnalogyIt works like a goal breakdown sheet: "speak English" splits into "get more chances to talk" and "build vocabulary", then goes down to "one online conversation a week".
How to rememberIn English it is a tree diagram: the trunk is the objective, and the branch tips are means you can act on tomorrow.
Exam points
ExamIn a tree diagram (系統図), carrying out a means on a lower level leads to reaching the objective (目的) just above it. This chain of objectives and means (手段) continues level by level.
A logic tree (ロジックツリー) breaks one problem or theme into its component elements, then breaks those into lower-level elements layer by layer.
Fewer inquiries
Fewer site visitors
Hard to spot in search results
Ads were stopped
Visitors do not reach the inquiry step
Too many fields to fill in
Contact point is hard to find
Branching by asking "why?" repeatedly makes it a diagram for digging into causes, and branching by "how?" makes it one for organizing solutions. Splitting each level with no gaps and no overlaps (MECE) prevents both oversights and discussing the same thing twice.
AnalogySplit the reasons your room gets messy into "too much stuff" and "nowhere to put things", break each down further, and you can see where to start.
How to rememberIt joins logic and tree, picturing a line of reasoning as the branches of a tree.
Exam points
ExamWhen a logic tree (ロジックツリー) is used for cause analysis, the problem that is occurring sits at the root and the causes producing it go on the lower branches.
Mix-upA tree diagram (系統図) and a logic tree (ロジックツリー) are both tree-shaped, but the tree diagram breaks an objective into means, while the logic tree serves both cause analysis and organizing solutions.
A concept map (コンセプトマップ) places several concepts as points, links related concepts with lines, and labels each line with words that describe the relationship.
When a line carries words such as "causes" or "is part of", two concepts and the line between them read as one sentence. It is used to check how pieces of learned knowledge connect, or to explain your thinking to others.
AnalogyIt is like a character chart for a TV drama: the characters are laid out and lines are labeled "parent and child" or "coworkers".
How to rememberConcept plus map: the concepts are place names and the lines are the roads.
Exam points
Mix-upA logic tree (ロジックツリー) is a one-way structure that splits one upper item into lower ones, while a concept map (コンセプトマップ) is a web in which any concepts can be linked freely.
Logic tree vs. Concept map
Aspect
Logic tree
Concept map
Key differenceHow items connect
One way, from upper to lower
Any concepts can be linked
Shape
Tree
Web
What a line means
Lower items come from splitting the upper one
Each line is labeled with its relationship
Key points
A fishbone chart is the same diagram as a cause-and-effect diagram: the result sits at the head, and causes are sorted along the bones.
On a control chart, points beyond the control limits or runs on one side of the center line are treated as signs of a change that chance can hardly explain.
In a tree diagram, a means on one level becomes the objective of the next, and splitting continues until concrete, actionable measures are reached.
Splitting the branches of a logic tree with no gaps and no overlaps (MECE) prevents oversights.
A concept map labels each line with its relationship, so the links between concepts read as sentences.