Exercise E Answers Examples

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Exercise E Answers Examples

  1. 1. Former EMBS students QUALITY MANAGEMENT Exercises E PROBLEMS 1. Management is concerned that workers create more product defects at the very beginning and end of a work shift than at other times of their eight hour workday. Construct a scatter diagram with the following data, collected last week. Is management justified in its belief? Products defects Hours of work Number of defects MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY 1 12 9 6 8 7 2 6 5 3 4 5 3 5 2 4 3 3 4 4 0 5 2 3 5 1 6 2 4 5 6 4 3 3 2 1 7 7 4 4 6 3 8 5 7 8 5 9 Total defects 44 36 35 34 31 Weekly Products Defects repartition 14 12 Monday Tuesday 10 Number of defects Wednesday 8 Thursday 6 Friday 4 Linéaire (Monday) Linéaire (Tuesday) 2 Linéaire (Wednesday) 0 Linéaire (Thursday) 0 2 4 6 8 10 Linéaire (Friday) Daily Hours of Work According to the scatter diagram and the added tendency curves we can make three comments regarding the management of the workers and give advices:
  2. 2. -Anyway we can see that especially on Monday and in general when we look at the points directly on the graph, that it is during the morning that the highest numbers of products defects are realized and the less at half of the working day. -Nevertheless the point all together are representing a U curve and are representing the fact that in the mornings and evenings but in less proportion, are the period of time when the most of the products defects are realized and the less during the mid-time working hours. So clearly the belief is justified that the defects are creating during beginning and ending working hours every day and also at the beginning and at the end of the week .(the highest point on the graph of the first working hour is on Monday and the highest point on the graph for the 8th working hour is on Friday). -The managing department should focus on the day of Monday because it is during this day that the more defect are producing comparing with all the other days of the week. -Focus their action of management during the beginning the working days and then on the ending periods.
  3. 3. 2. Perform a Pareto analysis on the following information: Reason for unsatisfying stay at hotel Frequency Unfriendly staff 6 Room not clean 2 Room not ready at check-in 3 No towels at pool 33 No blanket for pull-out sofa 4 Pool water too cold 3 Breakfast of poor quality 16 Elevator too slow or not working 23 Took too long to register 7 Bill incorrect 3 Total 100 Pareto analysis definition: Pareto principle states that only a “vital few” factors are responsive for producing most of the problems. This principle can be applied to quality improvement to extent that a great majority of problem (80%) are produced by a few key causes (20%). If we correct these few causes, we will have a greater probability of success. Perform a Pareto analysis: Analysis: Here we see that 20% of the causes: - No towel at pool; - Elevators too slow or not working; - Breakfast of poor quality; are responsible of almost 80% of quality issues. A large majority of the problems(80%), are produced by a few key causes (20%) which are those three. So in this configuration the quality manager should focus primarily on those three tasks.
  4. 4. Question 5: Perform a cause-and-effect diagram Definition A graphic tool used to explore and display opinion about sources of variation in a process. (Also called a Cause-and-Effect or Fishbone Diagram.) Purpose To arrive at a few key sources that contributes most significantly to the problem being examined. These sources are then targeted for improvement. The diagram also illustrates the relationships among the wide variety of possible contributors to the effect. The basic concept in the Cause-and-Effect diagram is that the name of a basic problem of interest is entered at the right of the diagram at the end of the main "bone". The main possible causes of the problem (the effect) are drawn as bones off of the main backbone. The "Four-M" categories are typically used as a starting point: "Materials", "Machines", "Manpower", and "Methods". Different names can be chosen to suit the problem at hand, or these general categories can be revised. The key is to have three to six main categories that encompass all possible influences. Brainstorming is typically done to add possible causes to the main "bones" and more specific causes to the "bones" on the main "bones". This subdivision into ever increasing specificity continues as long as the problem areas can be further subdivided. The practical maximum depth of this tree is usually about four or five levels. When the fishbone is complete, one has a rather complete picture of all the possibilities about what could be the root cause for the designated problem. The Cause-and-Effect diagram can be used by individuals or teams; probably most effectively by a group. A typical utilization is the drawing of a diagram on a blackboard by a team leader who first presents the main problem and asks for assistance from the group to determine the main causes which are subsequently drawn on the board as the main bones of the diagram. The team assists by making suggestions and, eventually, the entire cause and effect diagram is filled out. Once the entire fishbone is complete, team discussion takes place to decide what are the most likely root causes of the problem. These causes are circled to indicate items that should be acted upon, and the use of the tool is complete. The Ishikawa diagram, like most quality tools, is a visualization and knowledge organization tool. Simply collecting the ideas of a group in a systematic way facilitates the understanding and ultimate diagnosis of the problem. Several computer tools have been created for assisting in creating Ishikawa diagrams. A tool created by the Japanese Union of Scientists and Engineers (JUSE) provides a rather rigid tool with a limited number of bones. Other similar tools can be created using various commercial tools. Only one tool has been created that adds computer analysis to the fishbone. Bourne et al. (1991) reported using Dempster-Shafer theory (Shafer and Logan, 1987) to systematically organize the beliefs about the various causes that contribute to the main problem. Based on the idea that the main problem has a total belief of one, each remaining bone has a belief assigned to it based on several factors; these include the history of problems of a given bone, events and their causal relationship to the bone, and the belief of the user of the tool about the likelihood that any particular bone is the cause of the problem.
  5. 5. How to Construct:  Place the main problem under investigation in a box on the right.  Have the team generate and clarify all the potential sources of variation.  Use an affinity diagram to sort the process variables into naturally related groups. The labels of these groups are the names for the major bones on the Ishikawa diagram.  Place the process variables on the appropriate bones of the Ishikawa diagram.  Combine each bone in turn, insuring that the process variables are specific, measurable, and controllable. If they are not, branch or "explode" the process variables until the ends of the branches are specific, measurable, and controllable. Environment (place) Service (method) General presentation of the place Reactive Cleanness Welcoming Clarity Polite Dissatisfied customer of wedding reception caterer Staff (Wokring force) Food and beverage (material) Tools Motivated Choice Dishes Smilling Quality Cleaness Nice Taste Decoration Variety
  6. 6. 6. A refrigeration and heating company—one that installs and repairs home central air and heating systems—has asked your advice on how to analyze their service quality. They have logged customer complaints. Here's a recent sampling. Use the supplied template to construct a conventional cause-and-effect diagram. Place each of the complaints onto a main cause; justify your choice with a brief comment as necessary. First, the sampling is considered in the cause-and-effect diagram, as follows: Customers' complaints Associated Reference in the number diagram 1. "I was overcharged—your labour rates are too high." 1 Overcharging labour rates 2. "The repairman left trash where he was working." 2 Trash after leaving 3. "You weren't here when you said you would be. You should 3 Delay without call when you must be late." communication 4. "Your repairman smoked in my house." 4 Smocking employee 5. "The part you installed is not as good as the factory 5 Quality default of original." the material 6. "Your repairman was here for over two hours, but he 6 Un-seriousness of wasn't taking his work seriously." the employee 7. "You didn't tighten some of the fittings properly—the 7 Imprecision of the system's leaking." repair 8. "Your estimate of repair costs was WAY off." 8 Inappropriate cost estimation 9. "I called you to do an annual inspection, but you've done 9 Un-respect of more—work that I didn't authorize." contract 10. "Your mechanic is just changing parts—he doesn't have a 10 Bad knowledge of clue what's really wrong." employee 11. "Your bill has only a total—I wanted to see detail billing." 11 Lack of transparency in the bill 12. "Your testing equipment isn't very new—are you sure 12 Oldness of testing you've diagnosed the problem?" equipment 13. "One of the workmen tracked mud into my living room." 13 Uncleanness of employee
  7. 7. The cause-and-effect diagram PERSONNEL: MATERIALS: 10. Bad knowledge of employee 2. Trash after leaving 12. Oldness of testing equipment 4. Smocking employee 6. Un-seriousness of the employee 13. Uncleanness of employee PROBLEM / ISSUE: Dissatisfied customer of refrigeration and heating company's service PROCEDURES: EQUIPMENT: 1. Overcharging labor rates 5. Quality default of the material 3. Delay without communication 7. Imprecision of the repair 8. Inappropriate cost estimation 9. Un-respect of contract 11. Lack of transparency in the bill PERSONNEL: On my opinion, the personnel category gathers all the problems which are caused directly by a human behavior such as: the employee who left trash after working, the one who smoked while working, the un-seriousness of one, and the one who was not clean. All of these problems are related to a personal mistake of an employee in his relation with the customer, and which deals with unprofessional consciousness. MATERIALS: The materials category concerns: the bad knowledge of an employee and the oldness of testing equipment. The knowledge of the company’s employee and his tools are the two key materials this service requires. The material is necessary to provide the service; this is a mean to provide it, not an equipment delivered by the service. PROCEDURES: The procedures category includes: the overcharging of labor rates, the delay without contacting the customer, the inappropriate cost estimation, the un-respect of contract with the customer, and the lack of transparency in the bill. This is how the process, the service is done. These problems are related to company failures in its procedures realization, to the gap between the promised or desired service and delivered one. EQUIPMENT: The equipment category gathers: the quality default of a used material, and the imprecision of the repair done by an employee. This concerns the availability of the technical part of the provided service: the technical quality of a part, the quality of a repair, maintenance. This deals directly with the equipment.

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