The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

Line Graph: Examples

The Quality Toolbook > Line Graph > Examples

When to use it | How to understand it | Example | How to use it | Practical variations

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Example

A software programming team used a Line Graph during the test phase to track unfixed defects relative to release goals (See the illustration).

About half-way through the project it became evident that the goals would not be reached in time to meet the schedule. A subsequent improvement project identified that the team was spending time in low-skill testing when they could be better employed in higher skill defect fixing. An automatic testing harness was identified and installed, freeing time to fix defects. The release goals were met just in time.

Fig. 1. Example Line Graph

Other examples

• An accountant plots cumulative costs and revenue of a product on a line graph, identifying the break-even point where they cross. Improvement opportunities are then sought which will bring this point closer.
• A potter plots the temperature profile in her kiln during pot firing. She later correlates profiles with good and bad firings, learning how to control the temperature for an optimum pot. The result is a significant decrease in wastage. The greater reliability also allows her to fire more complex pots without the risk of losing the work done in throwing them.
• An automotive engineer hooks a set of strain gauges up to a computer and plots the stress at critical points on the body of a development vehicle during a test crash. This helps a stronger body to be designed which can also be produced using less material. The result is a savings in both money and lives.

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