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PARETO DIAGRAM

EXERCISE 1:

The General Manager of Quality Department, Proton Berhad wants to improve the quality of painting work of Proton cars. He decided to analyze the paint work processes to find out how he can reduce the amount of work that the Painting Department had to redo due to defects. Below are the type and frequency of defects of the painting work:

Type of Defect
Freq.
Cracks
25
Chips
76
Scratches
90
Uneven Surface
9
Rough Surface
6
Other
8

Draw the Pareto Diagram of the defects before and after improvement of 30% of the major defect.

Guidelines:

1. Write the data in order, from largest to the smallest.
Type of Defect
Freq.
Scratches
90
Chips
76
Cracks
25
Uneven Surface
9
Other
8
Rough Surface
6

2. Calculate the total.
Type of Defect
Freq.
Scratches
90
Chips
76
Cracks
25
Uneven Surface
9
Other
8
Rough Surface
6
Total
214

3. Calculate the cumulative values.
Type of Defect
Freq.
Percent
=
Scratches
90
30%
27
Chips
76
30%
22.8
Cracks
25
30%
7.5
Uneven Surface
9
30%
2.7
Other
8
30%
2.4
Rough Surface
6
30%
1.8
Total
214
30%

4. Calculate the percent of the total for each item.
5. Calculate the cumulative percentages.
6. Draw the bar chart.
7. Add the percent scale on the right side.
8. Plot the cumulative percentage points.
9. Draw the percent line.
10. Write labels and other information.

Sample table to build Pareto Diagram:

Item
Frequency
Cumulative Frequency
Percent of total
Cumulative Percentage
Scratches
90
90
30%
(90/214)*100= 42.1
Chips
76
166
30%
(166/214)*100= 77.5
Cracks
25
191
30%
(191/214)*100= 89.3
Uneven Surface
9
200
30%
(200/214)*100= 93.5
Other
8
208
30%
(208/214)*100= 97.2
Rough Surface
6
214
30%
(214/214)*100= 100
Total
214

EXERCISE2

Construct a Pareto diagram from the data given in the table below

Category
Frequency
Percent of total