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Six Sigma Quality and Defects per Million Opportunities
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Six Sigma Quality and Defects per Million Opportunities

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Questions and Answers

What is a limitation of the Cp value in measuring process capability?

  • It assumes the center of the output distribution is the same as the center of the product specification range (correct)
  • It does not account for variation in the process
  • It only measures the process width
  • It is only used for Six Sigma quality analysis
  • What is the purpose of the correction term (1 − K) in the Cpk metric?

  • To account for the process mean deviating from the target value (correct)
  • To reward processes with low defect rates
  • To adjust for differences in process and specification widths
  • To penalize processes with high variation
  • What does a Cpk value less than 1 indicate about a process?

  • The process is incapable and unreliable (correct)
  • The process is unreliable but capable
  • The process is capable and reliable
  • The process is capable but unreliable
  • What is the statistical likelihood of non-defects in a Six Sigma quality process?

    <p>99.99966%</p> Signup and view all the answers

    What is the relationship between D (design center) and X-bar (process average) when Cpk is identical to Cp?

    <p>D is equal to X-bar</p> Signup and view all the answers

    What is the purpose of the Measure phase in the Six Sigma methodology?

    <p>To determine how to measure the process and its performance</p> Signup and view all the answers

    According to the PPM table, what is the implication of a Cpk value of 0.50?

    <p>The process is incapable and may require 100% inspection</p> Signup and view all the answers

    What is the formula to calculate Defects per Million Opportunities (DPMO)?

    <p>Number of defects / (Number of opportunities for error per unit × Number of units) × 1,000,000</p> Signup and view all the answers

    What is the purpose of Process Capability Analysis in Six Sigma?

    <p>To assess the ability of a process to consistently meet or exceed a product's design specifications</p> Signup and view all the answers

    What is a 'Unit' in the context of Defects per Million Opportunities (DPMO)?

    <p>The item produced or being serviced</p> Signup and view all the answers

    What is the primary focus of process capability analysis in product design?

    <p>Evaluating the natural variability in the process</p> Signup and view all the answers

    What is the formula for calculating process capability (Cp)?

    <p>Cp = Specification width / Process width</p> Signup and view all the answers

    What is the significance of the scatter diagram in the example of K Computers' medical equipment cart?

    <p>It shows the relationship between conveyor speed and cut length</p> Signup and view all the answers

    Why is it not possible to cut each tube to exactly the same length in K Computers' medical equipment cart?

    <p>Because of the natural variability in the process</p> Signup and view all the answers

    What is the purpose of design tolerances for tubing parts in K Computers' medical equipment cart?

    <p>To designate how much the lengths can vary yet still fit together properly</p> Signup and view all the answers

    What is the purpose of process control charts in Six Sigma Quality?

    <p>To monitor process output and detect changes</p> Signup and view all the answers

    What does a point outside the upper and lower limits on a process control chart indicate?

    <p>The process has changed and is 'out of control'</p> Signup and view all the answers

    What is the typical range of values for a process that is capable and normal with sampling?

    <p>Between 1.00 and 2.00</p> Signup and view all the answers

    What is the percentage of confidence interval usually used to define the process width?

    <p>99 percent</p> Signup and view all the answers

    What is the primary purpose of process control analysis in Six Sigma Quality?

    <p>To monitor the output of a process to ensure it meets expected quality standards</p> Signup and view all the answers

    What should be done to a process when it is 'out of control'?

    <p>Stop, investigate, and correct the process</p> Signup and view all the answers

    What is the percentage of sample mean values that fall within 3 sigma of the center line in a bell-shaped curve?

    <p>99%</p> Signup and view all the answers

    What is the purpose of calculating the grand mean in the Xbar&R process?

    <p>To find the average of sample means</p> Signup and view all the answers

    What is the value of the mean range in the given example of Xbar&R process?

    <p>0.69</p> Signup and view all the answers

    What is the purpose of collecting data samples in the Xbar&R process?

    <p>To track the performance of a process over time</p> Signup and view all the answers

    What is the significance of the '3' in the equations for computing control limits?

    <p>The '3' establishes the width of the control limit, ±3σ, and can be changed to increase or decrease this interval.</p> Signup and view all the answers

    What does the p-chart in the Six Sigma Quality process control analysis show?

    <p>The p-chart shows defects spiking upward to sample 7, then back down to a low at sample 14, and then climbing again to sample 20.</p> Signup and view all the answers

    What do trends in a control chart typically indicate?

    <p>Trends indicate when successive points seem to fall along a line moving upward or downward.</p> Signup and view all the answers

    What do runs in a control chart typically indicate?

    <p>Runs indicate a series of points that show systemic changes in the process.</p> Signup and view all the answers

    What does hugging in a control chart typically indicate?

    <p>Hugging indicates points that appear so closely grouped that they seem to show no variation.</p> Signup and view all the answers

    What does periodicity in a control chart typically indicate?

    <p>Periodicity indicates plotted points that show the same pattern of change over equal intervals.</p> Signup and view all the answers

    What is the purpose of process control charts in Six Sigma Quality?

    <p>The purpose is to monitor and control processes to ensure they operate within predetermined limits.</p> Signup and view all the answers

    What does a point outside the upper and lower limits on a process control chart indicate?

    <p>A point outside the limits indicates a special cause of variation, which requires investigation and correction.</p> Signup and view all the answers

    What is the typical range of values for a process that is capable and normal with sampling?

    <p>The typical range is within 3σ of the center line.</p> Signup and view all the answers

    What should be done to a process when it is 'out of control'?

    <p>The process should be investigated, corrected, and brought back under control.</p> Signup and view all the answers

    Hyundai increased the number of workers on the _______________ team from 100 to more than 850.

    <p>quality control</p> Signup and view all the answers

    Hyundai instituted mandatory seminars for all workers on the importance of _______________.

    <p>quality</p> Signup and view all the answers

    Hyundai made capital investments in problem areas, including $30 million invested in a _______________ center to test electronic systems.

    <p>computer</p> Signup and view all the answers

    Hyundai placed first in the J.D. Power Initial _______________ Study in 2014.

    <p>Quality</p> Signup and view all the answers

    Quality is expected and must be delivered, as it offers firms a way of enhancing their _______________ and strategic position in the marketplace.

    <p>competitiveness</p> Signup and view all the answers

    Six Sigma Quality aims near ______ perfection

    <p>quality</p> Signup and view all the answers

    The ______ per Million Opportunities (DPMO) metric is used to describe the variability of the process.

    <p>Defects</p> Signup and view all the answers

    The design specification for a tube length is _____ mm ± 10mm.

    <p>1030</p> Signup and view all the answers

    The Six Sigma Methodology consists of ______ phases: Define, Measure, Analyze, Improve, and Control.

    <p>five</p> Signup and view all the answers

    The Cp is essentially the ratio of the _____ width to the process width.

    <p>specification</p> Signup and view all the answers

    Process capability analysis is a tool for assessing the ability of a process to consistently meet or exceed a product's ______ specifications.

    <p>design</p> Signup and view all the answers

    In the Six Sigma Methodology, the ______ phase determines how to measure the process and how it is performing.

    <p>Measure</p> Signup and view all the answers

    Managers in the past have chosen to set P = _____σ to define a range that covers about 99.7 percent of the output for processes that vary.

    <p>6</p> Signup and view all the answers

    A Cp value less than 1 would indicate that more than _____ percent of produced units will not meet design specifications.

    <p>0.3</p> Signup and view all the answers

    Graph C has the tallest and narrowest line with endpoints at _____ and _____, well inside the LSL and USL.

    <p>1024, 1036</p> Signup and view all the answers

    In Six Sigma Quality, the ______ monitors the output of a process to ensure that sample statistics are within the expected variation limits of the process.

    <p>process control analysis</p> Signup and view all the answers

    In a bell-shaped curve, ______ percent of sample mean values fall within 3 sigma of the center line.

    <p>99</p> Signup and view all the answers

    In the Xbar&R process, the range, R, is the difference between the ______ and smallest values.

    <p>largest</p> Signup and view all the answers

    The grand mean is calculated as the value of = (the ______ every x )/n.

    <p>summation</p> Signup and view all the answers

    The mean range is calculated as the value of = (the ______ of the every R)/n.

    <p>summation</p> Signup and view all the answers

    Process control charts or _______________ process control (SPC) are tools used to monitor process output.

    <p>statistical</p> Signup and view all the answers

    The process width is defined by a _______________ interval (usually 99 percent or 3σ).

    <p>confidence</p> Signup and view all the answers

    A point outside the upper and lower limits on a process control chart indicates that the process may have _______________.

    <p>changed</p> Signup and view all the answers

    Process control charts identify when a process has deviated from its normal _______________ operation.

    <p>operation</p> Signup and view all the answers

    When a process is 'out of control', the process operator should stop, _______________, and correct the process.

    <p>investigate</p> Signup and view all the answers

    Study Notes

    Six Sigma Quality

    • Aims to achieve near quality perfection, with a statistical likelihood of non-defects of 99.99966% of the time.

    Defects per Million Opportunities (DPMO)

    • A metric used to describe the variability of a process.
    • Requires three pieces of data: unit, defect, and opportunity.
    • Formula: DPMO = (Number of defects / (Number of opportunities for error per unit × Number of units)) × 1,000,000

    Six Sigma Methodology (DMAIC)

    • Define: identify customers and their priorities, a project suitable for Six Sigma efforts, and CTQs (critical-to-quality characteristics).
    • Measure: determine how to measure the process and how it is performing, and identify the key internal processes that influence CTQs.
    • Analyze: determine the most likely causes of defects and identify the key variables.
    • Improve: identify means to remove the causes of defects, confirm the key variables, and identify the maximum acceptance ranges of the key variables.
    • Control: determine how to maintain the improvements and put tools in place to ensure that the key variables remain within maximum acceptance ranges.

    Process Capability Analysis

    • A tool for assessing the ability of a process to consistently meet or exceed a product's design specifications.
    • Considers the tolerances allowed by product or service design specifications and the natural variability in the process.
    • Formula: Cp = Specification width / Process width

    Process Capability Analysis Examples

    • Example 1: K Computers' medical equipment cart, where piping is cut internally and a scatter diagram shows a positive relationship between conveyor speed and cut length.
    • Example 2: Deceptive Cp Value, where the process width and specification width are the same, but the center of the graph is not aligned with the design center, resulting in a Cp value that does not accurately reflect the process capability.

    Adjusted Cp Metric (Cpk)

    • Used to deal with non-centered process distributions.
    • Formula: Cpk = Cp × (1 - K), where K is a correction term.
    • Cpk is less than 1, indicating an unreliable process that cannot reliably meet design specifications.

    Cpk, PPM, and Process Management

    • Cpk values and their corresponding process implications:
      • 0.50: Process is incapable, 100% inspection may be needed.
      • 1.00: Process capable, normal sampling would be typical.
      • 1.33: Process capable, normal sampling would be typical.
      • 1.50: Process capable, no inspection may be needed.
      • 2.00: Process is very stable, no inspection may be needed.

    Process Control Analysis

    • Process Control Charts (SPC) are used to monitor process output to detect changes.
    • Intelligent systems plot and compare outputs to a set of limits for the upper and lower boundaries of the process width.
    • Process control charts identify when a process has deviated from its normal operation.

    Process Control Charts (Xbar&R)

    • An example of Xbar & R: tracking hard disk seek times to ensure the process of building the disks is under control.
    • Steps to create an Xbar & R chart:
      1. Collect data samples.
      2. Calculate the sample mean (x) for each sample.
      3. Calculate the range (R) for each sample.
      4. Calculate the grand mean.
      5. Calculate the mean range.

    Quality Definitions

    • Product quality is a product's fitness for consumption, which is determined by both design quality and conformance quality.
    • Design quality measures how well a product's designed features match up to the requirements of a given customer group.
    • Conformance quality measures whether a delivered product meets its design specifications.

    Dimensions of Quality

    • Performance: the degree to which a product meets or exceeds certain operating characteristics.
    • Features: presence of unique product characteristics that supplement basic functions.
    • Reliability: length of time a product performs before it must be repaired.
    • Durability: length of product life or the amount of use one gets before a product deteriorates.
    • Conformance: the degree to which a product meets its design specifications.
    • Aesthetics: subjective assessment of a product's look, feel, sound, taste, or smell.
    • Support/Responsiveness: competence of product support in terms of installation, information, maintenance, or repair.
    • Perceived Quality (Reputation/Assurance/Empathy): subjective assessment based on image, advertising, brand names, reputation, or other information indirectly associated with the product's attributes.

    Total Quality Management (TQM)

    • An integrated strategy aimed at embedding awareness of quality, aiming for near quality perfection (the statistical likelihood of non-defects: 99.99966% of the time).

    Six Sigma Quality

    • Defects per Million Opportunities (DPMO): a metric used to describe the variability of the process, requiring three pieces of data: unit, defect, and opportunity.
    • Six Sigma Methodology (DMAIC):
      • Define: identify customers and their priorities, a project suitable for Six Sigma efforts, and critical-to-quality characteristics.
      • Measure: determine how to measure the process and how it is performing, and identify the key internal processes that influence critical-to-quality characteristics.
      • Analyze: determine the most likely causes of defects and identify the key variables.
      • Improve: identify means to remove the causes of defects, confirm the key variables, and identify the maximum acceptance ranges of the key variables.
      • Control: determine how to maintain the improvements and put tools in place to ensure that the key variables remain within maximum acceptance ranges.

    Process Capability Analysis

    • A tool for assessing the ability of a process to consistently meet or exceed a product's design specifications, considering tolerances allowed by product or service design specifications and the natural variability in the process.
    • Cp = Specification width / Process width, where Cp is a measure of process capability.

    Process Control Analysis (p Chart)

    • A chart that plots the proportion of defectives in each sample, with the proportion of defectives (p) on the vertical axis and the sample number on the horizontal axis.
    • The graph has the upper limit at 0.09 and the lower limit at 0.00, and p-bar at 0.0335.
    • Interpreting Control Charts:
      • Trends: successive points seem to fall along a line moving upward or downward.
      • Runs: run of points that indicate systemic changes in process.
      • Hugging: points appear so closely grouped that they seem to show no variation.
      • Periodicity: plotted points show the same pattern of change over equal intervals.

    Quality Management

    • Hyundai's brand turnaround involved increasing the quality control team from 100 to 850 workers, instituting mandatory seminars, and involving the CEO in quality comparisons with rivals.
    • Hyundai invested $30 million in a computer center to test electronic systems and made capital investments in problem areas.

    Brand Turnaround at Hyundai - Results of Changes

    • Hyundai's brand loyalty surpassed that of Honda and Toyota, with five Hyundai cars among the "Best Bets" for safety, reliability, and fuel efficiency.
    • Genesis models made Hyundai a strong competitor in the luxury market, where excellent quality is imperative.
    • In 2014, Hyundai placed first in the J.D. Power Initial Quality Study, with an average of 90 problems per 100 vehicles, 20% fewer problems than those found in European, Japanese, and American cars.

    Six Sigma Quality

    • Defects per Million Opportunities (DPMO) is a metric used to describe the variability of a process.
    • DPMO requires three pieces of data: unit, defect, and opportunity.
    • The formula for DPMO is: Number of defects / (Number of opportunities for error per unit × Number of units) × 1,000,000

    Six Sigma Methodology (DMAIC)

    • Define: identify customers and their priorities, a project suitable for Six Sigma efforts, and CTQs (critical-to-quality characteristics).
    • Measure: determine how to measure the process and how it is performing, and identify the key internal processes that influence CTQs.
    • Analyze: determine the most likely causes of defects and identify the key variables.
    • Improve: identify means to remove the causes of defects, confirm the key variables, and identify the maximum acceptance ranges of the key variables.
    • Control: determine how to maintain the improvements and put tools in place to ensure that the key variables remain within maximum acceptance ranges.

    Process Capability Analysis

    • Process capability analysis is a tool for assessing the ability of a process to consistently meet or exceed a product's design specifications.
    • Specification width (S) is the design specification for a product.
    • Process width (P) is the actual range of outcomes generated by the production process.
    • Cp is the ratio of the specification width to the process width.
    • Cp = USL - LSL / 6σ ( Upper Specification Limit - Lower Specification Limit / 6 standard deviations)

    Process Control Analysis

    • Process control charts or statistical process control (SPC) are tools used to monitor process output to detect changes.
    • Intelligent systems plot and compare outputs to a set of limits for the upper and lower boundaries of the process width.
    • Process control charts identify when a process has deviated from its normal operation (when it is "out of control").
    • Xbar & R is an example of process control analysis, where sample means and ranges are used to track the process.

    Xbar & R

    • Xbar & R is used to track the process of building hard disks and ensure that the seek times are under control.
    • The process involves collecting data samples, calculating the sample mean and range, and calculating the grand mean and mean range.

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    Description

    This quiz covers the concept of Six Sigma quality and its relation to defects per million opportunities, including the measurement and calculation of DPMO.

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