100-Metodos-de-Qualidade-Total

DATA COLLECTION, ANALYSIS AND DISPLAY
Method 68
Bar charts
Purpose
To display discrete data collected by checksheets so that patterns can be
discovered.
When to use
In the early stages of problem-solving when a team is trying to find out
what is happening.
How to use
The number of times an event occurs is shown on the vertical axis. The
value at which it occurs is shown on the horizontal axis. Figure 1 shows a
bar chart of the reasons for in-test failure of a printed circuit board. Bar
charts are sometimes used in conjunction with Pareto analysis (Method 20).
Benefits
Bar charts give a simple pictorial representation of data.
Example
The following data were used to produce the bar chart in Figure 1:
Failure code Explanation No. failing
A Missing component 1,187
B Wrong component 980
C Wrongly inserted 767
0 Cold solder joint 420
E Short pins 409
F Test machine fault 221
The bar chart shows clearly which reasons for failure need to be addressed
to have any impact on the problem.