ITEC 3200 Quality Control and Statistical Analysis. Mid-Term Exam
A mid-term exam for ITEC 3200, focusing on quality control and statistical analysis in engineering.
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Susan Little
ITEC 3200 Mid- Term Exam
February 28, 2013
ITEC 3200 Quality Control and Statistical Analysis. Mid-Term Exam
Quality 5th Edition
Donna C. S. Summers
1) Define Common cause variation. (4 points)
Answer: Common cause variation refers to the inherent, natural, or background variation that exists
in any process or system. It is the variation that is always present due to factors that are part of the
process itself, such as machinery, environmental conditions, or human variability. This variation is
predictable and consistent over time and is generally considered as "normal" variation that does not
indicate a problem.
2) Define assignable cause variation. (4 points)
Answer: Assignable cause variation, also known as special cause variation, refers to variations in a
process that arise from specific, identifiable sources outside of the normal operating conditions.
These causes can include a malfunctioning machine, human error, material defects, or changes in
environmental conditions. Unlike common cause variation, assignable causes can often be corrected
once identified and are typically considered as indicators of issues that need attention.
3) Why is it important that we understand if the variation we see in a product/process comes from
common or assignable cause situations? (4 points)
Answer: Understanding whether the variation comes from common or assignable causes is essential
because it determines how the issue should be addressed. If the variation is due to common causes,
it may be inherent in the system and might require improvements to the overall process to reduce it.
However, if the variation is due to assignable causes, it is typically a sign of something that needs to
be fixed immediately (like equipment failure or human error). Properly identifying the cause allows
organizations to apply the right corrective action and maintain consistent product quality.
4) What was the primary addition to the concept of controlling the quality of products and services
that “Total Quality Management” added in the evolution of quality control methods. (4 points)
Answer: Total Quality Management (TQM) added a customer-focused, continuous improvement
approach to quality control. It emphasized the involvement of all employees in the organization in
improving processes, products, and services. Unlike earlier quality control methods that primarily
focused on inspection and defect detection, TQM fosters a culture where everyone in the
organization is responsible for maintaining quality, ensuring that issues are addressed before they
reach the customer.
5) Define a population. (5 points)
Answer: A population in statistics refers to the entire set of individuals, items, or data from which a
sample is taken for analysis. It represents the complete group under consideration, and the
population can vary depending on the context, such as all customers of a company, all products
manufactured by a factory, or all individuals in a particular geographical area. The goal is often to
make inferences about a population based on a representative sample.
6) Define a sample: (5 points)
Answer: A sample is a subset or a smaller portion of the entire population that is selected for the
purpose of conducting a study or analysis. The sample should represent the population well, and the
findings or conclusions drawn from the sample are often used to make inferences or generalizations
ITEC 3200 Mid- Term Exam
February 28, 2013
ITEC 3200 Quality Control and Statistical Analysis. Mid-Term Exam
Quality 5th Edition
Donna C. S. Summers
1) Define Common cause variation. (4 points)
Answer: Common cause variation refers to the inherent, natural, or background variation that exists
in any process or system. It is the variation that is always present due to factors that are part of the
process itself, such as machinery, environmental conditions, or human variability. This variation is
predictable and consistent over time and is generally considered as "normal" variation that does not
indicate a problem.
2) Define assignable cause variation. (4 points)
Answer: Assignable cause variation, also known as special cause variation, refers to variations in a
process that arise from specific, identifiable sources outside of the normal operating conditions.
These causes can include a malfunctioning machine, human error, material defects, or changes in
environmental conditions. Unlike common cause variation, assignable causes can often be corrected
once identified and are typically considered as indicators of issues that need attention.
3) Why is it important that we understand if the variation we see in a product/process comes from
common or assignable cause situations? (4 points)
Answer: Understanding whether the variation comes from common or assignable causes is essential
because it determines how the issue should be addressed. If the variation is due to common causes,
it may be inherent in the system and might require improvements to the overall process to reduce it.
However, if the variation is due to assignable causes, it is typically a sign of something that needs to
be fixed immediately (like equipment failure or human error). Properly identifying the cause allows
organizations to apply the right corrective action and maintain consistent product quality.
4) What was the primary addition to the concept of controlling the quality of products and services
that “Total Quality Management” added in the evolution of quality control methods. (4 points)
Answer: Total Quality Management (TQM) added a customer-focused, continuous improvement
approach to quality control. It emphasized the involvement of all employees in the organization in
improving processes, products, and services. Unlike earlier quality control methods that primarily
focused on inspection and defect detection, TQM fosters a culture where everyone in the
organization is responsible for maintaining quality, ensuring that issues are addressed before they
reach the customer.
5) Define a population. (5 points)
Answer: A population in statistics refers to the entire set of individuals, items, or data from which a
sample is taken for analysis. It represents the complete group under consideration, and the
population can vary depending on the context, such as all customers of a company, all products
manufactured by a factory, or all individuals in a particular geographical area. The goal is often to
make inferences about a population based on a representative sample.
6) Define a sample: (5 points)
Answer: A sample is a subset or a smaller portion of the entire population that is selected for the
purpose of conducting a study or analysis. The sample should represent the population well, and the
findings or conclusions drawn from the sample are often used to make inferences or generalizations
2
Susan Little
ITEC 3200 Mid- Term Exam
February 28, 2013
about the population as a whole. Sampling is used when it's impractical or impossible to collect data
from the entire population.
7) Define a random sample: (4 points)
Answer: A random sample is a type of sample where each member of the population has an equal
chance of being selected. This method ensures that the sample is unbiased and that every individual
in the population has an equal opportunity to be included. Random sampling is commonly used in
research to obtain a representative sample of a population without systematic bias.
8) Define a stratified and give one example. (4 points)
Answer: A stratified sample is a type of sampling method where the population is divided into
distinct, non-overlapping subgroups or "strata," and then a sample is taken from each of these strata.
This method ensures that all relevant subgroups are represented in the sample. For example, in a
survey about customer satisfaction, a company may divide its customers into strata based on age
groups (e.g., under 25, 26-40, 41-60, over 60), and then randomly select participants from each age
group to ensure all age demographics are represented.
9) for the following set of sample data calculate each of the values below. (12 points)
Sample data set: 10, 11, 12, 10, 12, 10, 9, 8, 13, 12, 14, 12, 11, 11, 13, 11, 11, 12, 14, 10
Mean:
Answer:
Median:
Answer:
Susan Little
ITEC 3200 Mid- Term Exam
February 28, 2013
about the population as a whole. Sampling is used when it's impractical or impossible to collect data
from the entire population.
7) Define a random sample: (4 points)
Answer: A random sample is a type of sample where each member of the population has an equal
chance of being selected. This method ensures that the sample is unbiased and that every individual
in the population has an equal opportunity to be included. Random sampling is commonly used in
research to obtain a representative sample of a population without systematic bias.
8) Define a stratified and give one example. (4 points)
Answer: A stratified sample is a type of sampling method where the population is divided into
distinct, non-overlapping subgroups or "strata," and then a sample is taken from each of these strata.
This method ensures that all relevant subgroups are represented in the sample. For example, in a
survey about customer satisfaction, a company may divide its customers into strata based on age
groups (e.g., under 25, 26-40, 41-60, over 60), and then randomly select participants from each age
group to ensure all age demographics are represented.
9) for the following set of sample data calculate each of the values below. (12 points)
Sample data set: 10, 11, 12, 10, 12, 10, 9, 8, 13, 12, 14, 12, 11, 11, 13, 11, 11, 12, 14, 10
Mean:
Answer:
Median:
Answer:
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Document Details
University
East Carolina University
Subject
Engineering