24 Questions
What is the main purpose of a scatter diagram?
To graph pairs of numerical data to look for a relationship between them.
What type of correlation is depicted by points that fall along a line or curve?
Strong positive correlation
What is the name of the chart used to determine if a process is in a state of statistical control?
Control chart
What is the main characteristic of a strong positive correlation?
The value of Y increases as the value of X increases.
What type of correlation is depicted by points that show no demonstrated connection between the two variables?
No correlation
What is the purpose of a control chart?
To determine if a process is in a state of statistical control.
What is the name of the chart used to study how a process changes over time?
Control chart
What is the characteristic of a weak positive correlation?
The value of Y increases slightly as the value of X increases.
What is the primary objective of root cause analysis?
To discover the root causes of problems
What is the main advantage of using Pareto charts?
They show the relative importance of problems
What is the 80/20 rule also known as?
The law of the vital few and the trivial many
What type of chart is used to analyze the frequency of problems or causes?
Pareto chart
What is the highest-level cause that sets in motion the entire cause-and-effect reaction?
The root cause of a problem
When would you use a Pareto chart?
When analyzing data about the frequency of problems or causes
What is the purpose of a Pareto chart?
To prioritize problems or causes by their relative importance
What does the curved line on a Pareto chart represent?
The cumulative total of the sample
What is the primary difference between the vital few and the trivial many in a Pareto Chart?
The vital few account for the majority of problems
What is the primary purpose of a histogram in quality control?
To display the distribution of numerical data
When is it appropriate to use a histogram in quality control?
When the data is numerical and you want to see the distribution
What is the primary purpose of a scatter diagram in quality control?
To analyze the relationship between two variables
When would you use a histogram to analyze whether a process can meet the customer's requirements?
When the data is numerical and you want to see the distribution
What type of graph is used to display the frequency of numerical data?
Histogram
What is the primary difference between a histogram and a scatter diagram?
A histogram displays numerical data, while a scatter diagram displays the relationship between two variables
When would you use a scatter diagram to analyze the relationship between two variables?
When analyzing the relationship between two variables
Study Notes
Basic Quality Tools
- Histograms are graphs that show the frequency of numerical data using rectangles.
- The height of a rectangle (the vertical axis) represents the distribution frequency of a variable.
- Use histograms when:
- Data are numerical
- Want to see the shape of the data's distribution
- Analyzing whether a process can meet customer's requirements
- Analyzing a supplier's process output
- Seeing if a process change has occurred over time
- Determining if outputs of two or more processes are different
- Communicating data distribution quickly and easily to others
Scatter Diagrams
- Scatter diagrams are two-dimensional graphical representations of a set of data.
- They graph pairs of numerical data with one variable on each axis to look for a relationship between them.
- Correlation patterns:
- Strong Positive: Y increases as X increases
- Strong Negative: Y decreases as X increases
- Weak Positive: Y increases slightly as X increases
- Weak Negative: Y decreases slightly as X increases
- Complex: Y is related to X, but the relationship is not easily determined
- No Correlation: No demonstrated connection between the two variables
Control Charts
- Control charts are used to determine if a process is in a state of statistical control or how much variation exists in a process.
- They are graphs used to study how a process changes over time.
- Also known as Shewhart Charts or Statistical Process Control Charts (SPCC)
Root Cause Analysis
- Root cause analysis is the process of discovering the root causes of problems to identify appropriate solutions.
- The root cause is the core issue that sets in motion the entire cause-and-effect reaction that ultimately leads to the problem(s).
Pareto Charts
- Pareto charts are powerful tools for showing the relative importance of problems.
- They contain both bars and lines, where individual values are represented in descending order by bars, and the cumulative total of the sample is represented by the curved line.
- Use Pareto charts when:
- Analyzing data about the frequency of problems or causes in a process
- Focusing on the most significant problems or causes
- Analyzing broad causes by looking at their specific components
- Communicating with others about data
- The 80/20 Rule (Pareto principle or law of the vital few & trivial many) states that roughly 80% of the effects come from 20% of the causes.
This quiz covers the basics of quality tools, focusing on Pareto charts and histograms, used in quality control and management.
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