Questions and Answers of Fundamentals Of Quality Control

(a) Refer to Exercise 12-1. Based on historical information, the company believes that the type of industry that the customer belongs to influences web development time. Suppose that there are four
Refer to Exercises 12-1 and 12-2. Suppose you believe that the impact of contract cost on web development time is dependent on the type of industry that the company is from.(a) What is the model
A financial institution wants to explore the relationship between a loan application approval time and the independent variables of annual salary of the applicant and years of employment.(a) What is
A retail company has information on the time taken (in days) to fulfill an order, the value of the order (in $10,000), the number of different types of products in the order, and the store location.
Refer to Exercise 12-9 and the regression model of time to fulfill an order based on order value.(a) Find a 95% confidence interval for the mean time to fulfill orders that have an order value of
Refer to Exercise 12-9 and the corresponding data shown in Table 12-13.(a) Based on a scatterplot of order fulfillment time versus order value, you decide to fit a quadratic model in order value.
Refer to the data in Table 12-13 on order fulfillment time.(a) You decide to develop a regression model using order value and the number of products in the order as predictors. Find the model
Refer to the data in Table 12-13 on order fulfillment time.(a) You decide to develop a regression model using order value, number of products, and location of the retailer as predictors. Find the
Refer to the data in Table 12-13 on order fulfillment time.(a) You believe that there are differences, in general, in the value of orders by location of the store. Consequently, its impact on order
Refer to the data in Table 12-14 on diabetic patients and the development of retinopathy.(a) Develop a regression model to predict the probability of development of retinopathy based on years of
Table 12-15 shows a sample of 30 observations on the choice of a vendor (A, B, or C) based on percent on-time delivery and unit cost of a product. Develop regression models to predict preference of a
Table 12-16 shows a sample of 30 randomly selected patients with chronic kidney disease (CKD). The gender, systolic blood pressure, and presence/absence of diabetes are also indicated. Higher the
Prostate-Specific Antigen Density (PSAD) results for patients are used to predict prostate cancer. Usually a cut-off value of greater than 0.14 is used for prediction.Biopsy results were used to
Refer to the prostate cancer data shown in Table 12-17 between the predicted results based on PSAD and the actual occurrence of cancer based on biopsy results. Can you conclude that there is a
Consider the following organizations. How would you define quality in each context?Specify attributes/variables that may measure quality. How do you integrate these measures? Discuss the ease or
An assemble-to-order hardware company has two types of central processing units(CPUs), C1 and C2, and two types of display monitors, M1 and M2. Unit C2 is slightly more complex then C1, as is M2
Suppose that the prevention and appraisal cost functions are given by Cp= 50q2 and Ca =10q, respectively, where q represents the degree of quality level (0< q< 1). The cost of reworking a unit is $5,
Refer to Exercise 2-2. For each situation, discuss the ease or difficulty of measuring service quality. What are some remedial measures?
Refer to Exercise 2-2. For each situation, explain what factors influence customer perception of quality and how they are to be managed.
The following companies are interested in conducting amarket survey of their products/services. Explain the possible sampling techniques that they might choose.(a) High-end automobiles(b) Cooking
Many companies have become global in their supply chain. In the quest for improved quality and cost reduction, raw material and/or components may be procured from different parts of the world.
Consider Exercise 3-23. Suppose, through a quality improvement effort, that the firstpass yield of each operation is improved to 98%. What is the percentage improvement in rolled throughput yield?
Consider Exercise 3-24. Through consolidation of activities, the number of operations has now been reduced to 10, with the first-pass yield of each operation being 98%. What is the percentage
Consider the original information in the Case Study, prior to process improvements, where the monthly demand is 2000 batches and the bottleneck is Operation 1. From a competitive perspective, DITE
Consider Exercise 3-36. In order to create a desirable operating environment, based on the process improvements in Operation 2, it was found that DITE was also able to reduce the fixed cost and the
Consider Exercise 3-37. DITE believes that it needs to market its product in an expanded environment. Assuming demand to remain the same, can DITE afford to spend $60,000 per month to remain
Explain the different types of measurement scales and give examples in the following situations:(a) Gallons of water to put out a fire by the fire department(b) Response time of an ambulance(c) Test
Refer to Exercise 4-7. For each situation, define a type I and a type II error in the appropriate context. Consider the costs of such errors and discuss the implications.
The following times (in minutes) to process hot-rolled steel are observed for a random sample of size 10:(a) Find the mean, median, and mode of the processing times. Interpret the differences between
The outside diameter of a part used in a gear assembly is known to be normally distributed with a mean of 40mm and standard deviation of 2.5 mm. The specifications on the diameter are (36, 45), which
The specifications for the thickness of nonferrous washers are 1.0±0.04 mm. From process data, the distribution of the washer thickness is estimated to be normal with a mean of 0.98mm and a standard
The number of times a Web server is accessed per minute is known to follow a Poisson distribution. A random sample of size 8, each over a minute, shows the number of times that the server is accessed
Explain why it is important to obtain feedback from customers on both perceived satisfaction and importance of specified survey items.
A random sample of 50 observations on the waiting time (in seconds) of customers before speaking to a representative at a call center is as follows:(a) Construct a histogram and comment on the
The pH values of a dye for 30 samples taken consecutively over time are listed rowwise:(a) Can we conclude that the sequence of pH values over time is nonrandom? Use α = 0.05.(b) Assume that dyes
Percentage investment in new-product development is monitored for a pharmaceutical company by quarter. The observations are listed rowwise:(a) Can we conclude that the sequence of investment
An automobile manufacturing company is attempting to cope with rising health care costs of its employees. It offers three types of plans. Based on a random sample of 200 employees selected last year,
shows the number who selected each plan.The same table also shows, for a random sample of 150 employees selected in the current year, the number who selected each plan. Can we conclude that employee
The impact of three different advertising techniques is being studied by a marketing firm. Sales, in thousand dollars, categorized in four groups are shown for each advertising technique for 200
A survey asked customers to rate their overall satisfaction with a service company as well as the speed in responding to their requests. For both questions, a rating scale of 1–5 was used with the
shows the tabulated frequencies based on responses to both questions. Does response speed influence overall satisfaction?Use α= 0.01. Find Cramer’s index of association. TABLE 5-16 Response Speed
Consider the five items on timeliness of operations as listed in Table 5-7. A summary of the survey responses on patient satisfaction for each item, by the percentage in each rating category, is
Summary data on ratings of patient satisfaction and importance for the survey item“waiting time prior to being seen by a physician” is shown in Table 5-19 for a total of 400 patients. Perceived
Acompany’s quality manager wants to estimate, with a probability of 0.90, the copper content in a mixture to within 4%.(a) How many samples must be selected if no prior information is available on
A manufacturer is considering replacement of an existing machine that performs an operation on a part. The variable costs are $0.38 per piece on the existing machine and$0.05 per piece on the new
In Exercise 5-31, if the initial inspection costs of the transmission systems is $1.00 per unit, what inspection policy should be followed using Deming’s kp rule?
Refer to Exercise 5-31, Suppose that the monthly production is 3000 units. What is the average savings in total inspection costs per month when using the policy found from Deming’s kp rule as
Explain the rationale behind placing the control limits at three standard deviations from the mean.
The diameter of a part produced by an automatic machine is a characteristic of interest.Based on historical data, the process average diameter is 15mm with a process standard deviation of 0.8 mm. If
The time to deliver packaged containers by a logistics company is found from samples of size 4. The mean and standard deviation of delivery times is estimated to be 140 hours and 6 hours,
A health care facility is monitoring daily expenditures for a certain diagnosis-related group (DRG). Individual observations are selected. After 50 samples, the average and standard deviation of
Discuss specific characteristics that could bemonitored through variable control charts, the formof data to collect, and the appropriate control chart in the following situations:(a) Waiting time to
Patient progress in a health care facility is monitored over time for a certain diagnosisrelated group according to a few vital characteristics (systolic blood pressure, diastolic blood pressure,
Discuss the importance of risk adjustment in monitoring mortality and related measures in a health care setting.
The time to be seated at a popular restaurant is of importance. Samples of five randomly selected customers are chosen and their average and range (in minutes) are calculated. After 30 such samples,
The advertised weight of frozen food packages is 16 oz and the specifications are 16± 0.3 oz. Random samples of size 8 are selected from the output and weighed. The sample mean and standard
In a gasoline-blending plant, the quality of the output as indicated by its octane rating is measured for a sample taken from each batch. The observations from 20 such samples are shown in Table
The average time (minutes) that a customer has to wait for the arrival of a cab after calling the company has been observed for random samples of size 4. The data for 20 such samples are shown in
Consider Exercise 7-32, which deals with the average wait time for the arrival of a cab. Using the data in Table 7-28, construct a geometric moving-average control chart. Use a weighting factor of
The percentage of potassium in a compound is expected to be within the specification limits of 18–35%. Samples of size 4 are selected, and the mean and range of 25 such samples are shown in Table
Refer to Exercise 7-45. Demonstrate if the existing process in making a decision on loan applications is capable of meeting a goal value of 12 weeks. Assuming a normal distribution of the
Refer to Exercise 7-45. Construct an exponentially weighted moving-average chart using a weighting constant of 0.2 for the decision-making process and comment. Is the existing process capable of
Refer to Exercise 7-48 and the revised process. Is this process capable of meeting a goal value of $1.5M for the standard deviation of the weekly amount invested?Construct an appropriate chart and
Refer to Exercise 7-48. Construct an exponentially weighted moving-average chart using a weighting constant of 0.2 for the weekly amount invested. Comment on the process. If it is desired to have a
Refer to Exercise 7-51 and the data in Table 7-35 on cardiac surgery patients. Conduct a risk-adjusted sequential probability ratio test using a false-alarm rate of 0.005.Assume that the chance of
For the patient data in Exercise 7-51 as shown in Table 7-35, construct a risk-adjusted exponentially weighted moving average (RAEWMA) chart using a weighting constant of 0.2 and a false-alarm rate
Refer to the Case Study in the chapter. Suppose the company decides to hire another associate to help with the delivery of orders. After operating for a month, the company estimates the updated
Refer to the Case Study in the chapter and Exercise 7-54. With the added associate for delivery, what is the mean total time for order processing and delivery for an order?What is the standard
Refer to the Case Study in the chapter and Exercise 7-54. Assume that the total time for order processing and delivery for an order is normally distributed. What is the probability of completing a
What are the advantages and disadvantages of the standardized p-chart as compared to the regular proportion-nonconforming chart?
Explain the conditions under which a u-chart would be used instead of a c-chart.
Which type of control chart (p, np,c, u, U, or charts for highly conforming processes)is most appropriate to monitor the following situations?(a) Number of potholes in highways(b) Proportion of
Every employee in a check-processing department goes through a four-month training period, after which the employee is responsible for their operation. The work of one employee who has been on the
The number of customers who are not satisfied with the service provided in a retail store is found for 20 samples of size 100 and is shown in Table 8-24. Construct a control chart for the proportion
Refer to Exercise 8-18. Management believes that the dissatisfaction rate is 3%, so establish control limits based on this value. Comment on the ability of the store to meet this standard. If
Health care facilities must conform to certain standards in submitting bills to Medicare/Medicaid for processing. The number of bills with errors and the number sampled are shown in Table 8-25.
Observations are taken from the output of a company making semiconductors.Table 8-26 shows the sample size and the number of nonconforming semiconductors for each sample. Construct a p-chart by
Refer to Exercise 8-21 and the data shown in Table 8-26. Construct a standardized p-chart and discuss your conclusions. TABLE 8-26 Items Nonconforming Observation Inspected Items Items Observation
The quality of service in a hospital is tracked by determining the proportion of medication errors; this is done by dividing the number of medication errors by 1000 patient-days for each observation.
Refer to Exercise 8-18 and the data shown in Table 8-24. Construct a control chart for the number of dissatisfied customers. Revise the chart, assuming special causes for points outside the control
The number of processing errors per 100 purchase orders is monitored by a company with the objective of eliminating such errors totally. Table 8-29 shows samples that were selected randomly from all
The number of dietary errors is found from a random sample of 100 trays chosen on a daily basis in a health care facility. The data for 25 such samples are shown in Table 8-30.(a) Construct an
The number of imperfections in bond paper produced by a paper mill is observed over a period of several days. Table 8-31 shows the area inspected and the number of imperfections for 25 samples.
Refer to Exercise 8-29. If we want to control the number of imperfections per 100m2, how would this affect the control chart?What would the control limits be? In terms of decision making, would there
The director of a pharmacy department is interested in benchmarking the level of operations in the unit.The director has definedmedication errors as being anyoneof the following: wrongmedication;
Nonconformities in automobiles fall into three categories: serious, major, and minor.Twenty-five samples of five automobiles are chosen, and the total number of nonconformities in each category is
Refer to Exercise 8-32. If the weighting systems were different (i.e., 10, 5, and 1), how would the centerline and the control limits change for theU-chart? Discuss changes, if any, in the inferences
Refer to Exercise 8-18. Construct an OC curve for the p-chart. If the process proportion of dissatisfied customers were to rise to 7%, what is the probability of not detecting this shift on the first
Refer to Exercise 8-27. Construct an OC curve for the c-chart. If the process average number of dietary errors per 100 trays increases to 10, what is the probability of detecting this on the first
Refer to Exercise 8-36. Set up 2σ control limits. What is the probability of detecting a change in the process average number of dietary errors per 100 trays to 8 on the first sample drawn after the
The number of heart surgery complications is rare. To monitor the effectiveness of such surgeries, data are recorded on the number of such procedures until a complication occurs. These complications
shows such data for a sequence of 25 complications. It is estimated from past data that the complication rate is 0.1%. Construct an appropriate control chart and comment on the process assuming a
Consider Exercise 8-38. If you were interested in detecting an improvement in the process using a one-sided limit, what should the minimum sample size be for an α of 0.005? What should it be for an
Consider Exercise 8-38 under the assumption that the complication rate is 0.1%. If you were to construct a p-chart using two-sided 3σ limits, what would the minimum sample size be to detect an
Consider Exercise 8-38. Determine the sensitivity of the control limits on the complication rate using values of 0.2% and 0.5%.
Consider Exercise 8-38 under the assumption that the complication rate is 0.1% and a type I error of 0.005. If you reduced the upper control limit to half of its previous value, what type of process
In a health care facility, it is known that nosocomial infections are rare. Table 8-38 shows the number of admissions between occurrences of nosocomial infections.Construct an appropriate control
Data from a city bank showing monthly loan applications for home mortgage and the number rejected are given in Table 8-39. Construct an appropriate control chart and comment on the loan approval
Refer to Exercise 9-13. Find the process capability indexCpk and comment on process performance. If the target value is 47.5 ppm, find the Cpm and Cpmk indices and comment on their values. If the
Consider the assembly of three components shown in Figure 9-22. The tolerances for these three components are given in Table 9-8. Assume that the tolerances on the components are independent of each

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