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Chapter 2 Basic Tools for Improving Quality. 7 Basic Tools by Ishikawa Histogram Pareto chart Scatter plot Control chart Cheek sheet Cause-and-effect.

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Presentation on theme: "Chapter 2 Basic Tools for Improving Quality. 7 Basic Tools by Ishikawa Histogram Pareto chart Scatter plot Control chart Cheek sheet Cause-and-effect."— Presentation transcript:

1 Chapter 2 Basic Tools for Improving Quality

2 7 Basic Tools by Ishikawa Histogram Pareto chart Scatter plot Control chart Cheek sheet Cause-and-effect diagram Defect concentration diagram

3 2.1 Histogram

4 Table 2.1 Example Data 2445365948 3170856287 8157686078 2725375665 4250533957 51 403463 5866544643 8255 7566 2132496979 5423506864 5364743065 6058526144 3252405949 8384357667 5556415947 6452287671 33 565169 5143727345 4145614246 58 635262

5 Histogram by Minitab

6 Histogram by Excel BinFrequency 296 3911 4918 5929 6920 7910 896 More0

7 2.2 Pareto Charts A Pareto chart is a bar graph that shows the relative frequencies of observations in a descending order. –draws its name from an Italian economist, Vilfredo Pareto (1848–1923) –J. M. Juran is credited with being the first person to apply it to industrial problems

8 Table 2.3 Nonconformities and Associated Monetary Losses Lot #DateNIScratchesML Broken Tips MLSpotsMLOthersML 20141100022$8636$1606$203$6 20262100023883917031023 201331000301004117882447 203241000187937164143559 203051000208128146153836 2028610002183391701028610 20407100019803315292523 201181000126629150518712 201091000146931149824610 2015101000167430148722916 202211100012662213641659 2021121000136827145112723 2024131000218335158133111 20231410002286291501026610 2018151000198023138620712 Totals15,0002821189479231412936468117

9 Pareto Chart on Nonconformities

10 Pareto Chart on Monetary Losses

11 2.3 Scatter Plots A scatter plot is another simple graphical device The simplest type is a bivariate scatter plot, in which two quantities are plotted. Scaling of the two axes is somewhat arbitrary A time sequence plot is a type of scatter plot in that data on one variable are plotted against a second variable, time. A probability plot is another type of scatter plot.

12 Table 2.4 Data for Quality Improvement Program Month No. of Employees Trained (000) Cost of Training (000) January1223 February1019 March1027 April1120 May915 June610 July814 August58 September69 October35 November23 December24

13 Table 2.4 Data for Quality Improvement Program

14 Variations of Scatter Plots Use number or special symbols for duplicated data points. Use “range frames”, instead of scales

15 2.4 Control Charts A control chart is a time sequence plot with “decision lines” added. These decision lines are used to try to determine whether or not a process is in control. –Type I and II errors

16 Typical Control Chart 12345678 9 10 Sample number Upper control limit Central Line Lower control limit 11 11 22 22  =011 22 33 95% 99.73% -1  -2  -3 

17 2.5 Check Sheet A check sheet is a means of recording historical data on causes of nonconformities or nonconforming units. –The general idea is to record all pertinent information relative to nonconformities and nonconforming units, so that the sheets can facilitate process improvement. –Such information might include notes on raw materials, machine performance, or operator changes.

18 2.6 Cause-and-Effect Diagram The cause-and-effect diagram was introduced in Japan in 1943 by Professor Kaoru Ishikawa of the University of Tokyo. –For that reason it is sometimes called an Ishikawa diagram; it has also been called a fishbone chart.

19 Cause-and-Effect Diagram

20 2.7 Defect Concentration Diagram It is simply a schematic diagram that shows the various sides of a unit of production, with the positions where nonconformities occur pinpointed.

21 Defect Concentration Diagram

22 2.8 The 7 Newer Tools Affinity Diagram Interrelationship Digraph Tree Diagram Prioritization Matrix Matrix Diagram Process Decision Program Chart Activity Network Diagram

23 2.8.1 Affinity Diagram An affinity diagram is a set of ideas about a particular topic that are grouped into clusters. The diagram is the end product of brainstorming that is performed in a prescribed manner.

24 2.8.1 Affinity Diagram

25 2.8.2 Interrelationship Digraph An interrelationship digraph is used for identifying and exploring causal relationships between related ideas. This is a step beyond an affinity diagram, as an interrelationship digraph is a figure with arrows indicating relationships between ideas.

26 2.8.2 Interrelationship Digraph

27 2.8.3 Tree Diagram A tree diagram is somewhat similar to a cause-and-effect diagram in that a desired effect (e.g., reducing delivery delays) can be shown pictorially as related to the factors that can lead to the effect. A tree diagram will generally more closely resemble a company organizational chart in appearance than a cause- and-effect diagram. A tree diagram is a more structured display than either an affinity diagram or an interrelationship digraph.

28 2.8.3 Tree Diagram

29 2.8.4 Prioritization Matrix A prioritization matrix is a relative ranking of issues jobs, objectives, products, and so on. The ranking is accomplished by comparing the components pairwise so that a logical and consistent ranking results.

30 2.8.4 Prioritization Matrix

31 2.8.5 Matrix Diagram A matrix diagram is used for showing relationships between two or more sets of ideas, projects, and so on. The matrix can have one of several different forms. At least five forms have been used: –C-shaped –L-shaped –T-shaped –X-shaped, and –Y-shaped

32 2.8.5 Matrix Diagram

33 2.8.6 Process Decision Program Chart A process decision program chart is a listing of undesirable events and corresponding contingency actions relative to planned actions. It is used when there is considerable concern about the possibility of negative unanticipated outcomes.

34 2.8.6 Process Decision Program Chart

35 2.8.7 Activity Network Diagram This is essentially a combination of two well-known techniques: PERT (Program Evaluation and Review) and CPM (Critical Path Method).

36 2.8.7 Activity Network Diagram

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