Quality Control Tools (2023)

Quality Control Tools (1)

“A man and his tools make a man and his trade” – Vita Sackville-West

As a Quality Engineer one of the most important skills you need is the ability to solve a problem or improve a process.

To do this successfully, you need the proper tools. In fact, there are 7 specific tool that you must know.

Kaoru Ishikawa once said “As much as 95% of quality problems can be solved with seven fundamental quantitative tools”.

These tools were first categorized as Quality Control Tools by Ishikawa in his book Introduction to Quality Control.

Does it seem odd that we’re in the Continuous Improvement section talking about Quality Control & Problem Solving?

It shouldn’t – problem solving is continuous improvement.

Improvements happen when we solve problems.

So, what are these 7 fundamental tools for problem solving & continuous improvement:

  • Flow Charts
  • Check Sheets
  • Pareto Charts
  • Cause & Effect Diagrams
  • Control Charts
  • Scatter Diagrams
  • Histograms

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Within this chapter, we will discuss when to use each tool along with how to construct and analyze them.

So why are these seven tools so effective?

They all share two characteristics that make them very effective in problem solving (and continuous improvement).

First – they are all visual tools. You’ve heard the saying – a picture is worth a thousand words. These tools prove that point.

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Second – they all deal with facts or data, not opinions or conjecture.

Problems are solved with facts and data.

Improvements are made with facts and data.

When we combine a fact-based approach with a visual tool we are able to solve problems more easily.

The other comment I’ll make about these tools is that they are often used in combination with each other, and I’ll provide examples of that as we go through each tool.

Lastly, I wanted to provide a link to a Youtube Playlist for the 7 QC Tools.

Let’s get started with the flow diagram.

An Easy Starter Quiz

Hey before you invest of time reading this chapter, try the starter quiz.

[WpProQuiz 68]

If you do really well, then you head down to the final quiz at the bottom.

A Flow Chart is a visual tool that depicts the flow or sequence of a process. This can include the flow of information, tasks, people, material or decision.

The Flow Chart’s value lies in its ability to visually communicate the steps and sequence of a process.

(Video) The 7 Quality Control (QC) Tools Explained with an Example!

The Flow Chart makes the complex become simple, and promotes a common understanding of a process, which is the foundation for improvement.

The Flowchart is an excellent starting point in the Problem-Solving Process, as it allows your problem-solving team to see the entire process and identify improvements.

Flow Charts are also powerful in their application. You can make them super detailed, or you can stay at a high level, depending on the goal of the flow chart.

One common mistake with flow charts is that they are often created in a conference room, away from where the process actually occurs.

There will always be a difference between the “theoretical” process that you believe is occurring, and the actual process that’s occurring.

You must go and see for yourself (Gemba), to truly understand the actual process. Go and talk with the folks who actually work the process to truly understand the process.

Common Flow Chart Symbols

To facilitate the communication process, it’s generally acceptable to use standard symbols with your flow charts. This will ensure consistency and reduce miss-communication.

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Flow Chart Example

Let’s say we’re a manufacturer of toasters, and we’ve been asked to put together a high-level flow diagram of the entire manufacturing process.

Remember, each of these steps in the process could have its own more detailed flow chart.

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Solving problems and making improvements requires data. Period.

The check sheet is a simple tool for collecting, organizing and analyzing data.

I would argue that when you combine the simplicity of the check sheet with the potential value associated with the collected data that the check sheet is the most powerful QC tool.

A Check Sheet is normally a table with defined rows and columns where the data collected is usually 1 check mark within each category. However, you can modify this concept of a data collection tool to meet a variety of different needs.

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The example above is very simply. Almost too simple.

The best check sheets contain something more than data, they contain meta data.

Meta data is data about the data – like who collected the data, when (date, shift or time) the data was collected, and where (location, line, equipment number) there data collection took place.

Without this meta data, the actual data can become ambiguous and lose its integrity (think data integrity).

A good check sheet is designed to have clear, unique & unambiguous data collection categories. If necessary, standard work (work instructions) can be created and distributed with the check sheet to ensure data is collected appropriately.

This can include illustrations to go along with the check sheet.

Let’s say we go back to our toaster example and see what a check sheet for final assembly rejects might look like. This also includes the meta data and illustrations to go along with it.

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This data can then be fed into a pareto chart to identify the “critical few” defects (Hint, it’s the electrical defect).

The Pareto Chart is a bar chart that allows for analysis of data in search of the Pareto Principle or the 80/20 rule.

The 80/20 rule was first identified by an Italian researcher, Vilfredo Pareto, who was studying wealth and land ownership in Europe, and found that 80% of the land in Europe was owned by 20% of the population.

What Pareto did not realize is that this 80/20 rule is a universal principle, and can be applied to a lot more than wealth distribution.

The 80/20 rule was popularized by Joseph Juran, who names the Pareto Chart after Vilfredo Pareto.

Juran went on to say that the Pareto Chart helps us separate the vital few from the trivial many.

Essentially, the pareto chart is a prioritization tool that allows us to focus on the issues that are causing the biggest problem, and thus maximize our impact.

Mechanically, the Pareto Chart is simply a bar chart that displays data that from various discrete categories. This data might come from a check sheet.

(Video) Seven Quality Control Tools Explained with Example | Invensis Learning

The categories of data are typically arranged from greatest to least on the X-axis.

The Y-axis is a count of defects, but this number can be cost, or any other variable. Pareto Charts also frequently include a cumulative frequency line to assist in the analysis.

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Let’s analyze this our Pareto Chart quickly. There are 15 total defect conditions (A-N).

The top 3 defects (Defects A, B & C) make up only 20% (3 out of 15) of the defect conditions, however they contribute to 72% of the total number defects.

IF we could eliminate just these 3 defect conditions, we could eliminate 72% of the defects.

That’s the Pareto Chart and the 80/20 Rule at work.

The Cause and Effect diagram is a visual tool to explore all the potential factors that may be causing or contributing to a particular problem (effect).

This tool was popularized by Kaoru Ishikawa and allows you to graphically capture all the potential causes of a problem, then select those which require further investigation.

The Cause & Effect Diagram is also commonly referred to as the Fishbone Diagram, the Ishikawa Diagram, Cause & Effect Matrix, C&E Diagram or the C-E Diagram.

The cause and effect diagram can be completed as part of a 3-step process.

Step 1 is to agree on the problem statement, this is the negative “effect” you’re experiencing. This might seem simple, but it’s important to align on the problem statement prior to continuing.

Step 2 is the brainstorming process which is facilitated by the 8M’s of the fishbone process (below), and should be used with a process flow chart and 5-Why technique to truly identify causes, and not simply stop at symptoms.

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The Ishikawa diagram has 8 major categories (The 8M’s) that might contribute to your problem which include:

  • Man – How do Humans interact with your product/process/equipment and how could that contribute to your problem.
  • Machine – What type of equipment or machinery are used in your process and how could a deviation here contribute to your problem.
  • Method – What type of process/procedure do you follow and what potential issues might contribute to your problem.
  • Materials – What type of material is used and how could any material deviations contribute to your problem.
  • Mother Nature – How does the environment interact with your product/process in a way that might contribute to your problem.
  • Measurements – What type of measurements and measurement equipment do you use and how might this relate to the problem.
  • Management – What are the attitudes, outlooks & priorities of management and how could this be contributing to your problem.
  • Maintenance – What type of maintenance/calibration activities are being performed on your machines or measurement equipment that could be contributing to your problem.

Once you’ve brainstormed and created a list of potential causes and contributing factors, you can move on to Step 3.

Step 3 is to prioritize an action plan of investigation steps that will help confirm or exclude the potential causes and factors.

Another underrated characteristic of the Cause & Effect Diagram is its effectiveness as a communication aid. Especially when you’re dealing with a very complex issue.

Let’s go through a quick example

Quality Control Tools (10)Cause & Effect Example

Let’s say you’re a Toaster Manufacturer and you received a customer complaint for a toaster that is not toasting.

Step 1 in the Cause and Effect process is to agree on a problem statement: The Toaster is not toasting.

With more data we could refine this problem statement to improve the brainstorming, but for now we will leave it generic.

We can always refine the problem statement as the investigation progresses.

Then we can go through the brainstorming process using the 8M’s to identify potential causes and contributing factors that require further investigation.

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You can see here we’ve excluded maintenance, machines and Management, and identified potential causes and contributing factors in other areas.

We can also prioritize the most likely contributing factors which should give the investigation actions to conclude the root cause of the problem.

For example, we agree that the most likely root cause is a faulty heating element, and we will focus our investigation here first.

A control chart is a statistically based tool that analyzes the variation of a process.

A control chart is a time-based line graph that reflects the behavior of a process over time including normal variation and any special cause variation.

A control chart can also be described as a visual communication tool that graphs analyzed data in real-time and reflects the stability of a process.

Remember – A good process is a stable process – we want stability.

An unstable process is unpredictable and results in both problems, and is a clear opportunity for improvement.

(Video) 7 Basic Quality Control Tools for Efficient Project Management

The details of the control chart, including the various kinds, how to create them, and how to analyze them can be found in the Statistical Process Control chapter.

This section is a high-level summary of the control chart, along with how it can be used to solve problems and improve processes.

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The control chart contains upper and lower control limits that are statistically based, which allow the user to identifying instances where the process appears to be behaving abnormally.

These control limits and centerline represent the “voice of the process” and are simply a reflection of the process – both the average value of your process and the natural variation of the process.

The primary benefit of a control chart is its unique ability to separate the normal variation within your process from the special cause variation.

Special cause variation causes problems. It represents an opportunity for improvement.

Normal cause variation can also be an opportunity for improvement, however reducing normal cause variation can be difficult because it can often require making substantial changes to the process itself.

Using control charts allows you to proactively monitor your process, detect when a problem is occurring (or has occurred), which is the starting point for an improvement project.

A control chart is like a scoreboard. It can be used at the end of an improvement project to indicate if an improvement was successful or not.

A Scatter diagram is a visual analysis tool that is meant to reflect the possible relationship between two variables.

The Scatter Plot visually plots pairs of data on an X-Y graph in order to reveal the relationship between the data sets.

This section will summarize the scatter diagram at a high level, and the Relationship Between Variables Chapter in Statistics will cover this topic in detail.

The relationship between the two variables can be positive, negative or non-existent. The strength of the relationship can also be analyzed visually by how closely the points fall on the line of best fit.

The strength of that relationship can be expressed mathematically using the Pearson Correlation Coefficient, which is a number that ranges from a strong positive correlation (+1) to a strong negative correlation (-1).

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Scatter Plots require pairs of data, one set of data in the pair is normally referred to as the Independent Variable (X) with the second half of the data set being your observed measurement also known as the Dependent Variable (Y).

When a Positive Correlation exists between two variables a positive increase can be expected from the dependent variable (Y) when the intendent variable (X) increases.

The opposite is true for the Negative correlation. A negative correlation means that when the independent variable (X) increases, the dependent variable (Y) will decrease.

No Correlation results when the two variables have no measurable effect on each other. That is a change in X, does not impact Y.

The scatter plot is often used in the problem-solving process when we’re studying a process to understand which input variables (independent variables) are contributing to a negative outcome in a response variable (dependent variable).

This chart is fairly easy to create using tools like excel or other statistical analysis packages, we can collect data using a check sheet, and we’re specifically collecting paired data.

Let’s take a look at an example of how we could use a scatter diagram to analyze two variables and assess the relationship between them.

Quality Control Tools (14)Scatter Diagram Example

FYI – below is a hypothetical situation. I’ve created this data as an example, however I believe the conclusions are likely accurate 😊.

Let’s say that I’m studying the various factors that affect performance on the CQE Exam.

I hypothesis that there is a relationship between quiz scores and the ultimate exam score.

So I run an experiment where I work with 14 people and have them take a quiz before the exam to determine if a relationship exists between these two variables.

Ultimately, I’d like to be able to predict their exam score based on the quiz score.

So I’ve taken these pairs of data, with the Quiz Score as the Independent Variable (X), and the Exam Score as the Dependent Variable and analyzed them using a Scatter Diagram.

Each pair of data represents a dot on the Scatter Plot, and I’ve included a linear regression line to reflect the relationship between these variables.

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This scatter diagram indicates that a strong positive correlation exists between these two variables (r = 0.8).

If you do well on the quiz, you’re likely going to do well on the exam.

(Video) Learn What the 7 Quality Control Tools Are in 8 Minutes

But can doing well on a quiz CAUSE you to do well on the exam. No.

This is a good opportunity to warn you about the difference between correlation and causation.

This is an example of correlation without causation.

These two variables highly correlate with each other because there are other factors like study time, study habits, or job performance that are CAUSING you to do well on both variables.

So, if you really want to do well on the exam, create healthy study habits, invest your time to study, reflect on what you’ve learned, put that into action and you will do well on the exam (and the quiz).

It’s not to say that this quiz is without value though. The quiz is an indicator of potential success on the exam.

You might have indicators like this in your process that perhaps do not relate back to quality or cost, but they can indicate if a problem exists.

The Histogram is a tool used to visualize the distribution of continuous data.

More specifically, a Histogram is a type of Bar Chart that graphs the frequency of occurrence of continuous data and is a useful tool for displaying, summarizing and analyzing data.

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Variation is all around us.

Every process or product has some level of variation.

Every data set you collect will have variation in it, and this variation will exist in a “Pattern”.

And the best way to see or understand this Pattern of variation is to graph your data using a Histogram.

There are different patterns of variation that may be revealed in a Histogram. The most common distributions, and their analysis, are discussed within the Probability Distribution section of Statistics, and 3 examples are shown below.

Typically, a distribution can be characterized by the central tendency of the data (Mean, Median Mode), and the “variation” (range, standard deviation, etc) within the data.

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Within the next section on Statistics, you’ll learn that many concepts and tools assume that data is normally distributed.

The histogram is a visual tool you can use as a gut check to see if your data set is approximately normal.

Lastly, in terms of creating a histogram, this can be done in excel, and many statistical software packages will create histograms for you, so I won’t go into that detail here.

As a Quality Engineer one of the most important skills you can have, is the ability to solve a problem or improve a process.

To do this successfully, you need to be able to apply the 7 QC Tools.

These 7 tools combine a fact-based approach with a visual tool that makes solving problems easier.

Below is a quick and simple review of the definition for each of the 7 tools discussed within this chapter.

A Flow Chart is a visual tool that depicts the flow or sequence of a process. This can include the flow of information, tasks, people, parts, material, etc.

The check sheet is a simple tool for collecting, organizing and analyzing data.

The Pareto Chart is a bar chart that allows for analysis of data in search of the Pareto Principle or the 80/20 rule.

The Cause and Effect diagram is a visual tool to explore all the potential factors that may be causing or contributing to a particular problem (effect).

A control chart is a time-based line graph that reflects the behavior of a process over time including normal variation and any special cause variation.

A Scatter diagram is a visual analysis tool that is meant to reflect the possible relationship between two variables.

A Histogram is a type of Bar Chart that graphs the frequency of occurrence of continuous data and is a useful tool for displaying, summarizing and analyzing data.

The Final Quiz

[WpProQuiz 69]

Next Chapter: Continuous Improvement Techniques

FAQs

What is quality control and its tools? ›

QUALITY CONTROL “Quality control is the regulatory process through which we measure actual quality performance, compare it with standards, and act on the difference” 7 Basic Tools • Pareto Chart • Check sheet • Cause & Effect Diagram • Control Chart • Histogram • Scatter Diagram • Stratification or Flow chart.

Why are 7 quality tools used for? ›

7 QC tools are a set of graphical data representation and problem-solving techniques. These seven basic quality tools are integral to any process improvement methodology, including Six Sigma, total quality management (TQM), etc. They help in troubleshooting a variety of quality-related issues.

How many types of QC tools are? ›

However, there are seven management tools for quality control that are the most common. Different tools are used for different problem-solving opportunities, and many of the tools can be used in different ways.

What are 4 types of quality control? ›

What are the four types of Quality Control? The four types of quality control are process control, control charts, acceptance sampling, and product quality control.

How do I use 7 quality tools? ›

7 Basic Quality Tool Templates
  1. Cause-and-effect diagram template (Excel)
  2. Check sheet template (Excel)
  3. Control chart template (Excel)
  4. Histogram template (Excel)
  5. Pareto chart template (Excel)
  6. Scatter diagram template (Excel)
  7. Stratification template (Excel)

What is check sheet 7 QC tools? ›

A check sheet is a structured, prepared form for collecting and analyzing data. This is a generic data collection and analysis tool that can be adapted for a wide variety of purposes and is considered one of the seven basic quality tools.

What does TQM mean? ›

Total Quality Management (TQM) is a management approach that seeks to provide long-term success by providing unparalleled customer satisfaction through the constant delivery of quality IT services.

What are 7QC tools PDF? ›

Keywords: Seven QC Tools; Check Sheet; Histogram; Pareto Analysis; Fishbone Diagram; Scatter Diagram; Flowcharts, and Control Charts.

What are quality control methods? ›

Quality control methods are strategic procedures that ensure the maintenance or improvement of a product's quality. Generally, these processes include training employees, creating measurable standards for output quality, and periodically testing items to detect any inconsistencies.

What are the 2 types of quality control? ›

What Are the 4 Types of Quality Control? There are several methods of quality control. These include an x-bar chart, Six Sigma, 100% inspection mode, and the Taguchi Method.

What are the 4 steps of quality control? ›

When broken down, quality control management can be segmented into four key components to be effective: quality planning, quality control, quality assurance, and quality improvement.

What are 7 QC tools PPT? ›

Seven Basic Tools of Quality
  • Introduction.
  • Stratification.
  • Check Sheet.
  • Control Chart.
  • Pareto Chart.
  • Cause & Effect Diagram.
  • Histogram.
  • Scatter Diagram.

What are the 3 levels of quality control? ›

From the top down these levels are:
  • Quality Management (QM)
  • Quality Assurance (QA)
  • Quality Control (QC)

What is the difference between QC and QA? ›

QA primarily focuses on the processes and procedures that improve quality, including training, documentation, monitoring and audits. QC focuses on the product to find defects that remain after development. QC professionals find these issues in a variety of ways, including software testing and beta or canary testing.

How many types of QA are there? ›

There are five types of Quality Assurance Function.

What are quality techniques? ›

Quality techniques include all tools, procedures and methods that are used in the field of quality management and quality assurance at all product creation levels to solve specific problems.

What's the goal of TQM? ›

The basic goal of Total Quality Management (TQM) is to involve all levels and functions of an organization in continually meeting and exceeding the customer's expectations of their daily operations, products or services.

What is Six Sigma concept in quality management? ›

Six Sigma is a quality management methodology used to help businesses improve current processes, products or services by discovering and eliminating defects. The goal is to streamline quality control in manufacturing or business processes so there is little to no variance throughout.

What are the types of check sheet? ›

Types of check sheets: Commonly used check sheets are tabular check sheets or tally sheets, location check sheets and graphical or distribution check sheets.

What is Pareto chart in quality control? ›

A Pareto Chart is a graph that indicates the frequency of defects, as well as their cumulative impact. Pareto Charts are useful to find the defects to prioritize in order to observe the greatest overall improvement.

What is scatter diagram in 7qc tools? ›

A Scatter diagram is one of the Seven Basic Quality Tools. It plots two sets of observations against each other; the horizontal axis represents one set of observations (independent variable) while the vertical axis represents the second set of observations (dependent variable).

Why do we need quality tools? ›

Using quality tools, companies identify production problems and quality control professionals implement solutions. You can benefit from learning about various management tools for quality control to ensure that the final product fulfils the quality requirements and conforms to industry standards.

What are the 7 quality tools give 1 example and the theorist of that tool? ›

These seven basic quality control tools, which introduced by Dr. Ishikawa, are : 1) Check sheets; 2) Graphs (Trend Analysis); 3) Histograms; 4) Pareto charts; 5) Cause-and-effect diagrams; 6) Scatter diagrams; 7) Control charts.

Which of these is not part of 7 QC tools? ›

1. Which of these is not a part of magnificent seven of SPC? Explanation: Pareto chart, check sheet, and scatter diagram are all parts of the 7 problem solving tools of SPC or magnificent 7 of SPC (statistical process control). 2k factorial design is a part of design of experiments.

Is FMEA a quality tool? ›

It is the technique par excellence of quality tools. They are the abbreviations of Failure mode and effects analysis (FMEA). FMEA is based on the application of a procedure for classifying potential failures based on their severity, frequency and detection capacity.

What is meant by IATF 16949? ›

IATF 16949:2016 is a technical specification aimed at the development of a quality management system which provides for continual improvement, emphasizing defect prevention and the reduction of variation and waste in the automotive industry supply chain and assembly process.

What is check sheet 7QC tools? ›

A check sheet is a structured, prepared form for collecting and analyzing data. This is a generic data collection and analysis tool that can be adapted for a wide variety of purposes and is considered one of the seven basic quality tools.

What are 7QC tools PPT? ›

Seven Basic Tools of Quality
  • Introduction.
  • Stratification.
  • Check Sheet.
  • Control Chart.
  • Pareto Chart.
  • Cause & Effect Diagram.
  • Histogram.
  • Scatter Diagram.

Which of these is not part of 7QC tools? ›

1. Which of these is not a part of magnificent seven of SPC? Explanation: Pareto chart, check sheet, and scatter diagram are all parts of the 7 problem solving tools of SPC or magnificent 7 of SPC (statistical process control). 2k factorial design is a part of design of experiments.

Why are quality tools important? ›

Quality Management tools help employees identify the common problems which are occurring repeatedly and also their root causes. Quality Management tools play a crucial role in improving the quality of products and services.

What is histogram in quality control? ›

A Histogram is a Quality Control Tool that graphically displays a data set. More specifically, a Histogram is a type of Bar Chart that graphs the frequency of occurrence of continuous data, and will aid you in analyzing your data.

What are the types of check sheet? ›

Types of check sheets: Commonly used check sheets are tabular check sheets or tally sheets, location check sheets and graphical or distribution check sheets.

What is flowchart in quality control? ›

A flowchart is a picture of the separate steps of a process in sequential order. It is a generic tool that can be adapted for a wide variety of purposes, and can be used to describe various processes, such as a manufacturing process, an administrative or service process, or a project plan.

What are 7 QC Tools PDF? ›

Keywords: Seven QC Tools; Check Sheet; Histogram; Pareto Analysis; Fishbone Diagram; Scatter Diagram; Flowcharts, and Control Charts.

What is TQM in management? ›

Total Quality Management (TQM) is a management framework based on the belief that an organization can build long-term success by having all its members, from low-level workers to its highest ranking executives, focus on improving quality and, thus, delivering customer satisfaction.

What is a Pareto diagram used for? ›

Pareto charts show the ordered frequency counts of data

These charts are often used to identify areas to focus on first in process improvement. Pareto charts show the ordered frequency counts of values for the different levels of a categorical or nominal variable. The charts are based on the “80/20” rule.

Videos

1. What Are the 7 Quality Tools for Quality Control
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2. The Seven basic quality tools
(Lean Strategies International LLC)
3. Basic Tools in Quality Control
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4. Learn 7 QC Tools in less than 8 minutes | Six sigma by MBB Mohit Sharma
(SIX SIGMA by MBB Mohit Sharma)
5. Quality Tools | Basic Tools Quality Control | Problem solving using 7 QC tools-أدوات الجودة
(Focusera For Quality Management System)
6. The 7 Management and Planning Tools Explained!
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