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Tools/Techniques
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Description
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Affinity Diagram
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Grouping of ideas, collected through brainstorming sessions, into meaningful groupings.
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Analysis of Variance
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A technique that subdivides the total variation of a set of data into meaningful
component parts associated with specific sources of variation for the purpose of
testing some hypothesis on the parameters of the model or estimating variance components.
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Attribute Sampling Plans
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A plan that allows users to count the number of conforming or non-conforming parts
and look for defects. The four types of attribute plans include single, double,
multiple & sequential.
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Bar Charts
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A bar chart displays collected data on parallel horizontal bars for comparative
analysis. Lengths are proportional to collected data.
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Box Plot
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A visual depiction of a dataset, including central tendency and dispersion. It can
be used when analyzing the overall pattern of data, when comparing two sets of data,
when there is not enough data for a histogram, or to summarize data.
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Brainstorming
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A technique used to generate a large number of ideas in a short period of time.
It helps to generate creative, original ideas with participation of the entire group.
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Brain Writing
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A nonverbal form of brainstorming. Ideas are written on paper by team members then
papers are exchanged and more ideas are written.
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Cause and Effect Diagram
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A diagram that relates causes and effects. It sorts ideas into useful categories
for determining root cause of a problem.
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Checksheet
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A prepared form used for collecting and analyzing data. It can also be used to record
that steps to a process have been completed.
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Control Charts
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A methodology for monitoring process & identifying when a process is operating “in
control/out control” (within known statistical boundaries). The chart helps to monitor
changes in process variability, stability, &/or central tendency over time. Chart
is used to determine adjustment of process is required. Types of control charts
include:
- X-Bar and R Chart
- X-Bar and S Chart
- Individuals Chart
- 1X-MR Chart
- Median and Range Chart
- Median and S Chart
- Moving X and Moving Range Chart
- Cusum Chart
- EWMA Chart
- Target Chart
- Nominal Chart
- X-Bar, R (within), and R (piece to piece)
- P Chart
- NP Chart
- C Chart
- U Chart
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Correlation Studies/Coefficient
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A study refers to the measure of the relationship between two sets of numbers or
variables. Correlation Coefficient – describes the magnitude and direction of the
relationship between two variables.
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Cost of Quality
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Cost of quality is the broad categories of internal & external failure costs, appraisal
costs, & prevention costs. It is the sum of the costs associated with providing
poor quality products & services. Also called ‘cost of quality’.
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Cp
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Capability Index is the ability to produce products conforming to a given specification
regardless of mean location. It is a ratio of tolerance specified to process capability.
Cp = Tolerance /6s.
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Cpk
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Capability Index is the ability to produce products confirming to given specifications
considering mean. Cpk = min of (USL – mean) or (mean – LSL)/3s.
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Critical to Quality
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Requirements that are most important to customers.
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CUMSUM Charts
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A control chart based on CUMmulative SUMs. These charts can detect small process
shifts faster than Shewhart control charts.
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Defects per Million Opportunities
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It gives additional insight into a process by including the number of opportunities
for failure.
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Descriptive Statistics
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Used to describe data. Examples of descriptive statistics include mean, median,
mode, standard deviation, maximum, minimum, and percentiles.
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Design of Experiments (DOE)
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Systematic method of evaluating the effect of the input variables to response variable.
It is used to evaluate the effect of variation to the output, based on input variables.
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EVOP Designs
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A method of conducting designed experiments on an ongoing process without interrupting
affecting its efficiency.
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EWMA Charts
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Exponentially Weighted Moving Average – a control charting methodology that utilizes
historical data at an exponentially diminishing weighted value.
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Fault Tree Analysis
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An analysis that identifies possible failure modes and associated probabilities.
It is the opposite of FMEA.
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Fishbone Diagram
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See Cause and Effect Diagram
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Force Field Analysis
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An analytical tool that identifies opposing aspects of a change, the positive forces
that support the change and negative forces that try to prevent it.
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Full Factorial Design
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Full Factorial experiment is the experimental design running all possible combinations
of all levels of all factors.
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Fractional Factorial Design
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A designed experiment strategy that assesses several factors/variables simultaneously
in one test, where a partial set of all possible combinations of factor levels are
tested to more efficiently identify important factors.
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Gage R&R (repeatability & reproducibility) Study
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The evaluation of measuring and identifying inherent variations by using different
gage operators at different times. Related concepts includes precision, accuracy,
repeatability, reproducibility, bias, gage linearity, gage stability.
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Histogram
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A graphical representation of the sample frequency distribution that describes the
occurrence of grouped items. It is a bar chart displaying the frequency of data
in a column format. It is one of the SEVEN TOOLS OF QUALITY.
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Hypothesis Testing
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A statistical hypothesis is a statement or claim about an unrealized true state
or nature.
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Indices of Variability
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Measures of Central Tendency, Mode, Median and Mean, and their corresponding measures
of spread.
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Interaction Plots
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An interactions plot is a plot of means for each level of a factor with the level
of a second factor held constant. Interactions plots are useful for judging the
presence of interaction.
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Main Effect Plots
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Use Main Effects Plot to plot data means when you have multiple factors. The points
in the plot are the means of the response variable at the various levels of each
factor, with a reference line drawn at the grand mean of the response data. Use
the main effects plot for comparing magnitudes of main effects.
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Matrix Diagram
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A diagram that graphically shows the relationship between groups of information.
It can be used when identifying how one group of items relates to another, for example,
when relating customer requirements to elements of a process.
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Mixture Designs
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Mixture experiments are a special class of response surface experiments in which
the product under investigation is made up of several components or ingredients.
In these situations, the response is a function of the proportions of the different
ingredients in the mixture.
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Monte Carlo Simulation
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Randomly generates values for uncertain variables over and over to simulate a model.
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MultiVari Charts
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A chart that to graphically display sources of variability. It displays the variance
within units, between units, between samples & between lots. than
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Multivoting
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A technique used to narrow a large list of possibilities to a smaller list or a
final selection.
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Non-parametric Tests
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Non-parametric tests are those that make no assumptions about the distribution of
the data. They are therefore more robust when data do not have well-behaved distributions.
They are generally used to investigate hypotheses about samples as a whole, rather
than about properties such as means.
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Normalized Yield
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The geometric average throughput yield one would expect at any given step in the
process. Analogous to the "typical" yield. For a k -step process, the normalized
yield would be the kth root of the rolled throughput yield. A note of caution: This
metric can be misleading if the throughput yields of the process steps vary a great
deal.
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Nominal Group Techniques
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A method of group brainstorming that encourages contributions from everyone. Each
team member writes down their ideas and in turn, states one idea from their list.
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Normal Probability Plot
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A method for determining whether a set of data takes the form of a normal distribution.
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Pareto Chart
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A graphical tool for analyzing and ranking problem causes from most significant
to least significant. It is a bar chart listing the identified causes of a problem
in order of their frequency or importance to it.
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Pareto Principle
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Around 80% of the problems often seem to be produced by around 20% of all the contributing
causes. It suggests that most effects, around 80%, come from relatively few, around
20%, of the causes.
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PDCA Cycle
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The plan-do-check-act cycle for making improvements or changes. The steps are: (1)
develop the improvement plan, (2) do the plan on a small scale, (3) review and analyze
the results, (4) take action based on what you learned.
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Pp
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Process Performance index is defined as the tolerance width divided by the process
performance, irrespective of the process centering.
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Ppk
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Is the process performance index which accounts for process centering.
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Probability Distributions
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A probability distribution relates the values of a characteristic with their probability
of occurrence. Types of probability distributions include:
- Binomial
- B negative Binomial
- Exponential
- Geometric
- Hyper Geometric
- Normal
- Poisson
- Uniform – discrete
- Uniform – continuous
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Process Capability
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The capability of a process to make product that meet specification.
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Process Mapping
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A Flow chart is a visual representation of the process steps done showing tasks.
Process Mapping provides additional information such as inputs, outputs, supplier,
customer , matrix. .
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Process FMEA
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The Process FMEA (PFMEA) is a disciplined analysis of the part's processes with
the intent to prevent the process-based failure modes prior to the first production
run, before money is spent on machines, tooling, etc. The focus is to prevent, or
at least detect, changes in the process variables, which could lead to a deviation
from the design requirements.
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Quality Function Deployment (QFD)
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A structured method used to identify customer needs, translate them into a realizable
product or service parameters, and guide the implementation process.
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Relations Diagram
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A diagram that shows cause and effect relationships. It helps a group analyze the
links between different aspects of a complex problem.
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Reliability
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The probability that a product will perform its intended function under stated conditions
for a given period of time.
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Run Charts
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Run charts are used to analyze processes according to time or order. Run charts
are useful in discovering patterns that occur over time.
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Regression
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Regression is used to understand the relationship between two or more variables.
Regression analysis makes it possible to predict one variable from the knowledge
about the other.
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Silos
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Empirical study of relationships between one or more responses and input variable
factors. The technique is used to determine the ‘best’ set of input variables to
optimize a response and or gain a better understanding of the overall system response
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Rolled Throughput Yield
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Rolled Throughput Yield (defect-based)--the probability of being able to pass a
unit of product or service through the entire process defect-free.
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Sampling Distributions
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The distribution of the values of a quality characteristic in all possible units
that can be sampled according to a specified sampling scheme.
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Scatter Diagram
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A diagram that helps to identify relationships between two variables. It is a two
or three dimensional graph that plots coordinates and shows relationships between
two or three variables.
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Stem and Leaf Plot
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Very similar to a histogram; the stem reflects the significant portion of the data
and the leaf (bars of the chart) reflects remaining portion of the data.
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Survey
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A technique used to collect data about the knowledge and opinions of a targeted
group of people. Types of surveys include written questionnaires, interviews, and
focus groups.
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Story Board
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A visual display of thoughts. It makes all facets of a process, organization, plan,
or concept visible at once.
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Taguchi Designs
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Robust parameter design technique, which is an engineering method for product/process
design that minimizes variation and/or sensitivity to noise.
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Tree Diagram
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A diagram that identifies actions to solve a problem or implement a solution. It
is also called a “How-How Diagram.”
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Why -Why Diagram
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A diagram that is used to help identify the root causes of a problem. It can help
determine both short term and long term solutions.
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Z Tests
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Calculation of how many sigmas fit between the process output average and the closest
specification limit
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