Evidence of Product #5 Seven Basic Tools of Quality Control

Alejandro Vazquez Ortiz II 19-01
Evidence of Product #5
Seven basic tools of Quality Control

1. Stratification
2. Histogram
3. Check sheet (tally sheet)
4. Cause and effect diagram (fishbone or Ishikawa diagram)
5. Pareto chart (80-20 rule)
6. Scatter diagram (Shewhart chart)
7. Control chart
BONUS: FLOWCHART
1. Stratification
Stratification is a method of dividing data into subcategories and classify

data based on group, division, class, or levels that helps in deriving
meaningful information to understand an existing problem.
How way it works is: You divide data into subcategories and classify data
based on a group, division, class, or levels that helps deriving important
information to understand the current situation or problem.
Benefits:
 Helps you determine the meaning of the information
 Reveals patterns that would not have been seen if they data
was clumped together
 It helps you organize the information in a simple way
2. Histogram
The purpose of the histogram is to study the density of data in any given
distribution and
understand the
factors or data
that repeats
more often. It
helps in
prioritizing factors
and identify
which are the
areas that need
utmost attention
immediately. It has structure like a bar graph, each bar within it represents a
group while the height of the bar represents the frequency of data whiting
that group. It works better with things that can be listed in chronological
order.
Benefits:
 Help you represent frequency distribution of data clearly and
concisely amongst different groups of a sample
 It helps to visualize the distribution of the data.
 When you Use the data presented in the histogram, you can
regulate statistical information.
3. Check sheet / Tally sheet
The purpose of a checklist is to list down the important things or events in a

tabular / metric format and keep on updating or marking the status in which
they are in or the status on their occurrence which helps understands the
progress, defect patterns and even causes for those same defects.
A check sheet can be a structured table for collecting data and analyzing it.
When the information is quantitative, the check sheet can also be called a
tally sheet.
Benefits:
 Simplicity, It helps visualize and comprehend the information better
 Can be used real time with minimal process disruption
 Can be stored for use later and compared with other check sheets
collected at different times or locations
4. Cause-and-effect diagram (also known as a fishbone or Ishikawa

diagram)
The purpose of this diagram is to identify all root causes behind a problem.
Introduced by Kaouru Ishikawa introduced the fishbone diagram, which
helps in identifying the various causes / factors leading to an effect /
problem and helps in making a connection between them. To identify the
source of variation the causes are usually grouped into the next categories:
 People
 Methods
 Machines
 Material
 Measurements
 Environment
Benefits:
 It prioritizes further analysis and helps you take corrective action.
 It helps you locate bottlenecks in the process.
 It helps you identify the root cause of the problem.
5. Pareto chart (80 – 20 Rule)
The function of Pareto chart is to highlight the most important factors that
are the reason for major causes of problems and failures.
It revolves around the concept of 80-20 rule which underlines that in any
process. 80% of problem or failure is caused by 20% of few major factors
which are often referred as vital few, whereas remaining 20% of problem or
failure is caused by 80% of many minor factors which are also referred as
trivial many.
The pareto char has bars graphs and line graphs where individual factors
are represented by a bar graph in descending order of their impact and the
cumulative total is shown by a line graph.
Benefits:
 It helps you segregate the problems and their causes.
 It helps you focus on solving the few causes generating the most
problems.
 It shows you the problems to focus on to get a significant
improvement.
6. Scatter diagram
The function of it is
to establish a
relationship
between problems
(overall effects) and
causes that are
affecting.
Is a statistical tool
that depicts
dependent
variables on Y –
Axis and
independent
variable on X – axis plotted as dots on their common intersection points.
Benefits:
 It is the best method to show you a non-linear pattern

 Observation and reading are straightforward.
 The range of data flow; the maximum and minimum value, can be
determined.
7. Control chart (Shewhart Chart)
The function of a control chart is to determine if the process is stable and

capable within the current conditions.
Is a statistical chart which helps in determining if an industrial process is
whiting control and capable to mee the customer defined specification
limits?
Data is plotted against time in X- axis, it will always have a central line
(average), an upper line for the upper control limit and a lower line for the
lower control limits. These lines are determined from historical data. Experts
can draw conclusions about whether the process variation is consistent (in
control, affected by common causes of variation) or is unpredictable (out of
control, affected by special causes of variation). It helps in differentiating
common causes from special cause of variation.
Benefits:
Useful when process is out of control
Identify causes that result in large shifts, i.e. useful in diagnosis
The patterns of the plot on a control chart diagnosis possible cause
and hence indicate possible remedial actions
 Flowchart
Some sources will swap out stratification to instead include flowcharts as
one of the seven basic QC tools. Flowcharts are most used to document
organizational structures and process flows, making them ideal for
identifying bottlenecks and unnecessary steps within your process or
system.
Flow-charting the steps of a process provides a picture of what the process
looks like and can shed light on issues within the process.
Benefits:
Effective Coordination
Effective Analysis
Instant Communication

Evidence of Product #5 Seven Basic Tools of Quality Control

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Alejandro Vazquez Ortiz II 19-01

Seven basic tools of Quality Control

Stratification is a method of dividing data into subcategories and classify

The purpose of a checklist is to list down the important things or events in a

4. Cause-and-effect diagram (also known as a fishbone or Ishikawa

 It is the best method to show you a non-linear pattern

The function of a control chart is to determine if the process is stable and

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