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The 7 Basic Quality Tools

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The 7 Basic Quality Tools

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  1. The 7 Basic Quality Tools Michele Cano

  2. Agenda • Introductions • The 7 Basic Tools • Exercises • Break • The 7 Basic Tools continued • Exercises • Group Discussions

  3. What are they? The seven basic tools according to Ishikawa are: • Check sheets • Flow charts • Graphs & Histograms • Pareto diagram • Cause and effect diagram • Scatter diagram • Control chart

  4. Why use tools? • To make data visible • Measure • Improve

  5. 1.Check sheets • What is a check sheet? • A form or sheet used to record data.

  6. Function of Check Sheets According to Ishikawa 1982, check sheets have the following functions: • Production Process distribution checks • Defective item checks • Defective location checks • Defective cause checks • Check-up confirmation checks • Others

  7. Example of a simple check sheet. (for car valet operation)

  8. Example of a simple process check sheet. (attributes)

  9. FlowchartsPROCESS MAPPING • Process mapping is an essential first step. • It identifies all of the process activities, sequence and responsibilities. • This can either be in a written format, or as a flowchart.

  10. FlowchartsPROCESS MAPPING (Written format)

  11. Flowcharting • Flowcharting is a graphical tool for analysing processes. • Constructing flowcharts leads to a better understanding of processes. • Better understanding of processes is a essential for improvement

  12. FlowchartsSome standard symbols


  14. HACCP Hazard Analysis and Critical Control Points Businesses are required to ‘identify any step in the activities of the food business which is critical to ensuring food safety and ensure that adequate safety procedures are identified, implemented, maintained, and reviewed.

  15. Steps involved in HACCP • Identify the Hazard • Identify points when you need to have control measures (control points) • Decide what control measures are needed • Implement those controls • Monitor

  16. Exercise Draw / evaluate a flowchart for one of the following processes: • Making a cup of coffee or tea • Cutting the grass • Booking a flight on-line • Organising a surprise birthday party

  17. 3. Graphs & Histograms Graphs, in various forms are used to aid understanding and analysis of collected data sets.

  18. GraphsBAR CHARTS • This is the data set shown graphically. • It highlights the major problems for all to see.

  19. Graphs • This graph shows production output for February.

  20. Graphs • The graph below shows categories of customer complaint.

  21. Rules for Graphing • Use titles and indicate when the data was collected • Ensure the scales are clear and represent the data accurately. • Always keep in mind the reason why the graph is being used.

  22. Exercise Graphs • You are the marketing director of XZY automotive, a new Scottish company. You have organised a local survey to rate your car against other small cars. • 30 people were polled and the results are shown below. • Xzy, ka, Clio, Clio, ka, fiesta, xzy, ka, 206, xzy, fiesta, fiesta, xzy, polo, fiesta, 206, 206, polo, 206, fiesta, fiesta, fiesta, polo, xzy, polo, fiesta, xzy, xzy, ka, xzy. • You have decided to Graph the results as part of your marketing drive. Choose and explain your choice of graph.

  23. What is a Histogram? • The Histogram shows the distribution of one characteristic for one period of time.

  24. What is a Histogram? • Is this a histogram?

  25. What is a Histogram? • The answer to the previous question is NO • The Histogram shows the distribution of one characteristic for one period of time.

  26. When is a Histogram Used? • To look at one particular set of results, for one characteristic at one period of time • To look for patterns in a process • To help understand data

  27. Histograms • The following data was collected when measuring the bow (warp) of a plastic component. The specification is less than 8 x10-3 mm (zero – 8). • This can be plotted as a histogram because we have quantitative data and target limits.

  28. 6 5 4 3 Frequency 2 1 0 6 9 0 1 2 3 4 5 7 8 Bow (10-3mm) Histograms

  29. What is a Histogram? Exercise • Sort the data about male weights into appropriate sets, then plot a histogram.

  30. 4. Pareto Analysis Separating the ‘vital few’ from the ‘trivial many’ Juran

  31. What is Pareto Analysis? • Pareto analysis is a method to help prioritise actions. • It is a Bar Chart displayed in a particular way either in order of importance (frequency, relative cost, etc).

  32. Household repairs over the last 10 years Cost £ per Total cost Problem frequency occurrence £ Light bulb fails 100 0.6 60 Broken central heating pump 1 190 190 Broken window 2 50 100 Leaking taps 16 2.5 40 Faulty central heating boiler 1 3000 3000 Leaking radiators 3 15 45 ParetoExample: The information to be represented on a Pareto diagram normally would have already been collected.

  33. House repairs 1998-2008 120 100 80 frequency Occurence 60 Cum % 40 20 0 window central heating central heating Broken Broken Faulty Leaking taps bulb fails radiators Light Leaking Fault ParetoPareto Chart The data are then displayed graphically. Firstly in terms of frequency.....

  34. House repairs 1998-2008 Total cost £ 3500 3000 2500 2000 1500 Total cost £ 1000 500 0 Faulty Broken Broken Light Leaking Leaking central central window bulb fails radiators taps heating heating boiler pump Pareto ... and then by cost.

  35. ExerciseProduce a Pareto Diagram for the data in the separate handout.

  36. 6. Cause and Effect Diagrams (Ishikawa) using brainstorming A method to help identification of the root causes of an effect (usually a problem).

  37. cause and effectWhat is Brainstorming? • A way to get creative ideas. • A way to get everyone’s views. • A way to generate alternatives.

  38. cause and effectPotential Uses (Brainstorming) • For identifying areas for improvement. • For finding potential causes of problems. • For developing possible preventive actions.

  39. Give wild and unusual ideas. Aim for quantity. Build on ideas of others. Encourage participation. Evaluate or criticise. Stop to soon. Allow domination or idea ownership. cause and effectSome Guidelines (Brainstorming) Do’s Don'ts

  40. Simple Rules for Brainstorming 1. Works best with a group of six to twelve members. 2. Ideas are taken from one member at a time, in rotation. 3. Ideas are written on a flip chart or OHP transparency. 4. If a response is not immediately forthcoming the member should pass. 5. No idea is too obvious or stupid.

  41. Simple Rules for Brainstorming 6. Ideas should not be enlarged upon at this stage. 7. The leader is there to lead the group, not to provide ideas. 8. The process is repeated until ideas dry up. 9. The ideas are then discussed and can be criticised but not the people that made them. 10. Eliminate the unlikely causes and identify those with high possibilities using cause screening - put those on a fishbone diagram.

  42. Ranking • Group discussion of likely causes and ease of fixing. • Individual selection of 3-5 most likely. • Paired comparisons

  43. Group discussion (Ranking) Group discusses if each possible cause is • N – Not likely • S - Somewhat likely • V - Very likely And the ease of fixing • N - Not easy • S - Somewhat easy • V - Very easy

  44. cause and effectIndividual Ranking • Each person privately selects 3 - 5 items from the list • Each person ranks their selection in order of priority • Allocate values of 1 most important, 2 next, 3 next, • The marks are then totalled for each item • The item having the lowest total is then judged to • have the highest priority.

  45. Paired Comparisons • The group preselects 6 – 8 most important causes. • Each person completes a paired comparison grid. • Scores are added using a vote matrix. • Highest score is most important

  46. cause and effectWhat is a Cause and Effect Diagram? • The process of a cause and effect diagram consists of defining an effect in terms of possible causes and is normally carried out in the form of a Brainstorming session. • The principal causes are typically Man, Materials, Methods or Machines. However you can also use Environment, Marketing, Management, Money etc. depending upon the exact situation.

  47. Cause and Effect Analysis • sub-causes can then be added • Finally, the most likely causes are then identified for further investigation. • These relationships are displayed pictorially in the form of a fishbone structure.

  48. cause and effectLayout: Method Man Sub-Cause Sub-Cause Sub-Cause Effect Sub-Cause Sub-Cause Sub-Cause Materials Machines