This document provides an overview of quality tools that can be used for continuous improvement. It outlines 7 basic quality tools - flow chart, cause and effect diagram, check sheet, histogram, Pareto chart, scatter diagram, and stratification. For each tool, it describes what the tool is, when it should be used, how to construct it, and provides an example. It also discusses using pivot tables instead of manual check sheets for summarizing large datasets. The agenda outlines using these tools to analyze processes and reports to deliver more important information instantly through transformation.
4. Seven Basic Quality Tools
"The Basic Seven."
Build your quality journey and Process Improvement skills by mastering these
tools.
1. Cause-and-effect diagram (also called Ishikawa or fishbone chart):
Identifies many possible causes for an effect or problem and sorts ideas into
useful categories.
2. Check sheet: A structured, prepared form for collecting and analyzing data;
a generic tool that can be adapted for a wide variety of purposes.
3. Histogram: The most commonly used graph for showing frequency
distributions, or how often each different value in a set of data occurs.
5. Seven Basic Quality Tools
4. Pareto chart: Shows on a bar graph which factors are more significant.
5. Scatter diagram: Graphs pairs of numerical data, one variable on each axis,
to look for a relationship.
6. Stratification : A technique that separates data gathered from a variety of
sources so that patterns can be seen (some lists replace "stratification" with
"flowchart" or "run chart").
7. Control charts : Graphs used to study how a process changes over time.
Details of each Basic Quality Tools are provided in the Section “Quality Tool
Box”
7. Quality Tool Box – Flow Chart
Flowchart
Also called: process flowchart, process flow diagram.
Description
A flowchart is a picture of the separate steps of a process in sequential order.
Elements that may be included are: sequence of actions, materials or services
entering or leaving the process (inputs and outputs), decisions that must be
made, people who become involved, time involved at each step and/or process
measurements.
The process described can be anything: a manufacturing process, an
administrative or service process, a project plan. This is a generic tool that can
be adapted for a wide variety of purposes.
) to see if they agree that the process is drawn accurately.
8. Quality Tool Box - Flow Chart
When to Use a Flowchart
• To develop understanding of how a process is done.
•To study a process for improvement.
•To communicate to others how a process is done.
•When better communication is needed between people involved with the same
process.
•To document a process.
•When planning a project.
9. Steps in Making Flow Chart
Flowchart Basic Procedure
Materials needed: Sticky notes or cards, a large piece of flipchart paper , marking
pens.
Steps
• Define the process to be diagrammed. Write its title at the top of the work surface.
• Discuss and decide on the boundaries of your process: Where or when does the
process start? Where or when does it end? Discuss and decide on the level of detail to
be included in the diagram.
• Brainstorm the activities that take place. Write each on a card or sticky note.
Sequence is not important at this point, although thinking in sequence may help
people remember all the steps.
• Arrange the activities in proper sequence.
• When all activities are included and everyone agrees that the sequence is correct,
draw arrows to show the flow of the process.
• Review the flowchart with others involved in the process (workers, supervisors,
suppliers, customers
11. Basic Quality Tool No 1 : Cause-and-Effect Diagram
Also called Fishbone Diagram, Ishikawa Diagram
Description
•The fishbone diagram identifies many possible causes for an effect or problem.
•It can be used to structure a brainstorming session.
•It immediately sorts ideas into useful categories.
When to Use a Fishbone Diagram
• When identifying possible causes for a problem.
• Especially when a team’s thinking tends to fall into ruts.
12. Basic Quality Tool No 1 : Cause-and-Effect Diagram
Double Click on file to
construct the diagram
Fishbone Diagram Procedure
Materials needed: flipchart or whiteboard, marking pens. Microsoft Office
Excel 97-2003 Worksheet
5.Agree on a problem statement (effect). Write it at the center right of the
flipchart or whiteboard. Draw a box around it and draw a horizontal arrow
running to it.
2. Brainstorm the major categories of causes of the problem. If this is difficult
use generic headings:
Methods
Machines (equipment)
People (manpower)
Materials
Measurement
Environment
14. Basic Quality Tool No 1 : Cause-and-Effect Diagram
MANUAL METHOD
OPTIONAL. USE
Fishbone Diagram Procedure - continuation
EXCEL TEMPLATE
1. Write the categories of causes as branches from the main arrow.
3. Brainstorm all the possible causes of the problem. Ask: “Why does this
happen?” As each idea is given, the facilitator writes it as a branch from the
appropriate category. Causes can be written in several places if they relate to
several categories.
5. Again ask “why does this happen?” about each cause.
Write sub-causes branching off the causes.
Continue to ask “Why?” and generate deeper levels of causes. Layers of
branches indicate causal relationships.
9. When the group runs out of ideas, focus attention to places on the chart
where ideas are few.
15. Basic Quality Tool No 1 : Example of Cause-and-Effect
This fishbone diagram was drawn by a manufacturing team to try to understand the source
of periodic iron contamination. The team used the six generic headings to prompt
ideas. Layers of branches show thorough thinking about the causes of the problem.
Major Categories
Possible causes
Possible causes?
Sub-causes Sub-causes
EFFECT
Possible causes (Problem)
Sub-causes
Major Categories
16. Basic Quality Tool No 2 : Check sheet
Description
A check sheet is a structured, prepared form for collecting and analyzing data.
This is a generic tool that can be adapted for a wide variety of purposes.
When to Use a Check Sheet
•When data can be observed and collected repeatedly by the same person or
at the same location.
•When collecting data on the frequency or patterns of events, problems,
defects, defect location, defect causes, etc.
17. Basic Quality Tool No 2 : Check sheet
Check Sheet Procedure
•Decide what event or problem will be observed. Develop operational
definitions.
•Decide when data will be collected and for how long.
•Design the form. Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis.
MANUAL METHOD OPTIONAL. If using Excel, use
•Label all spaces on the form. Pivot Table
•Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use.
•Each time the targeted event or problem occurs, record data on the check
sheet.
18. Basic Quality Tool No 2 : Check sheet Example
The figure below shows a check sheet used to collect data on telephone
interruptions. The tick marks were added as data was collected over several
weeks.
19. Instead of using manual check sheet, we will use Pivot
Table to summarize large data.
Make sure all Data Filter are not active
20. Instead of using manual check sheet, we will use Pivot
Table to summarize large data.
21. Instead of using manual check sheet, we will use Pivot
Table to summarize large data.
The table format is ready ! Choose
which ever information to be
summarized
22. Instead of using manual check sheet, we will use Pivot
Table to summarize large data.
Example ..Summary of Number of
Cases by Branch Name
23. Basic Quality Tool No 3 : Histogram
Description
A frequency distribution shows how often each different value in a set of data
occurs. A histogram is the most commonly used graph to show frequency
distributions. It looks very much like a bar chart, but there are important
differences between them.
When to Use a Histogram
•When the data are numerical.
•When you want to see the shape of the data’s distribution, especially when
determining whether the output of a process is distributed approximately
normally.
•When analyzing whether a process can meet the customer’s requirements.
•When seeing whether a process change has occurred from one time period to
another.
24. Basic Quality Tool No 3 : Histogram Double Click on file to
construct Histogram.
Note : Use “Paste
Values”
Histogram Construction
Collect at least 50 consecutive data points from a process.
Use the histogram worksheet to set up the histogram. Microsoft Office
Excel 97-2003 Worksheet
Histogram Analysis
Before drawing any conclusions from your histogram, satisfy yourself that the
process was operating normally during the time period being studied.
If any unusual events affected the process during the time period of the
histogram, your analysis of the histogram shape probably cannot be
generalized to all time periods.
Analyze the meaning of your histogram’s shape.
25. Basic Quality Tool No 3 : Histogram
Typical Histogram Shapes and What They Mean
Normal. A common pattern is the bell-shaped curve known as the “normal
distribution.” In a normal distribution, points are as likely to occur on one side of
the average as on the other.
Example : Distribution of heights (in cm) of all employees.
26. Basic Quality Tool No 3 : Histogram
Typical Histogram Shapes and What They Mean
Skewed. The skewed distribution is asymmetrical because a natural limit
prevents outcomes on one side. The distribution’s peak is off center toward the
limit and a tail stretches away from it.
For example, a distribution of analyses of time difference between employees
arriving at work (clock in time) and official company start time.
Or , differences in actual turn around to resolve certain types of complaints
compared to goal for that segment.
These distributions are called right- or left-skewed according to the direction of
the tail.
TAIL
This is right-skewed since
the tail is at our right
27. Basic Quality Tool No 3 : Histogram
Typical Histogram Shapes and What They Mean
Double-peaked or bimodal.
The bimodal distribution looks like the back of a two-humped camel.
The outcomes of two processes with different distributions are combined in one
set of data.
For example, a distribution of production data from a two-shift operation might
be bimodal, if each shift produces a different distribution of results. Stratification
often reveals this problem.
28. Basic Quality Tool No 4 : Pareto Chart or Pareto Analysis
Based on 80-20 Rule :
80% of the problem is caused by 20% of the causes
Description
A Pareto chart is a bar graph.
The lengths of the bars represent frequency or cost (time or money), and
are arranged with longest bars on the left and the shortest to the right.
In this way the chart visually depicts which situations are more significant.
When to Use a Pareto Chart
•When analyzing data about the frequency of problems or causes in a
process.
•When there are many problems or causes and you want to focus on the
most significant.
•When analyzing broad causes by looking at their specific components.
29. First Example of Pareto Chart
Example 1 shows how many customer complaints were received in each of five
categories of processes or departments.
30. Second Example of Pareto Chart
Example 2 takes the largest category, “documents,” from Example #1, breaks it
down into six categories of document-related complaints, and shows cumulative
values.
If all complaints cause equal distress to the customer, working on eliminating
document-related complaints would have the most impact, and of those,
working on quality certificates should be most fruitful.
31. Basic Quality Tool No 4 : Pareto Chart Double Click on file to
construct Pareto Chart
Pareto Chart Procedure Note : Use “paste Values”
Decide what categories you will use to group items. (Horizontal Axis or X Axis)
Microsoft Office
Decide what measurement is appropriate. Common measurements are Excel 97-2003 Worksheet
frequency, quantity, cost and time. (Vertical Axis or Y Axis)
Decide what period of time the Pareto chart will cover: One work cycle? One
full day? A week?
Collect the data, recording the category each time. (Or assemble data that
already exist.)
Subtotal the measurements for each category.
32. MANUAL METHOD
Basic Quality Tool No 4 : Pareto Chart OPTIONAL. USE
EXCEL TEMPLATE
Construct and label bars for each category.
Place the tallest at the far left, then the next tallest to its right and so on. If
there are many categories with small measurements, they can be grouped as
“other.”
Steps 8 and 9 are optional but are useful for analysis and communication.
Calculate the percentage for each category: the subtotal for that category
divided by the total for all categories. Draw a right vertical axis and label it
with percentages.
Calculate and draw cumulative sums: Add the subtotals for the first and
second categories, and place a dot above the second bar indicating that sum.
To that sum add the subtotal for the third category, and place a dot above
the third bar for that new sum. Continue the process for all the bars.
Connect the dots, starting at the top of the first bar. The last dot should
reach 100 percent on the right scale.
33. Construct Pareto of M&M colors
Produce a Pareto Chart of colors of M&M chocolate in
a pack of M&M
Compare differences between your colleagues
80% of your M&M content consists of what color?
34. Basic Quality Tool No 5 : Scatter Diagram
Also called: scatter plot, X–Y graph
Description
The scatter diagram graphs pairs of numerical data, with one variable on each
axis, to look for a relationship between them. If the variables are correlated, the
points will fall along a line or curve. The better the correlation, the tighter the
points will hug the line.
When to Use a Scatter Diagram
•When you have paired numerical data.
•When trying to determine whether the two variables are related, such as…
•When trying to identify potential root causes of problems.
•After brainstorming causes and effects using a fishbone diagram, to
determine objectively whether a particular cause and effect are related.
•When determining whether two effects that appear to be related both occur
with the same cause.
35. Basic Quality Tool No 5 : Scatter Diagram Double Click on file to
construct Scatter
Diagram
Scatter Diagram Procedure
•Collect pairs of data where a relationship is suspected.
•Draw a graph with the independent variable on the Microsoft Office
Excel 97-2003 Workshee
horizontal axis and the dependent variable on the vertical
axis. For each pair of data, put a dot or a symbol where
the x-axis value intersects the y-axis value. (If two dots
fall together, put them side by side, touching, so that you
can see both.)
•Look at the pattern of points to see if a relationship is
obvious. If the data clearly form a line or a curve, you
may stop. The variables are correlated.
36. Basic Quality Tool No 5 : Scatter Diagram MANUAL METHOD
OPTIONAL. USE
Scatter Diagram Procedure EXCEL TEMPLATE
•Divide points on the graph into four quadrants. If there are X points on the graph,
Count X/2 points from top to bottom and draw a horizontal line.
Count X/2 points from left to right and draw a vertical line.
If number of points is odd, draw the line through the middle point.
•Count the points in each quadrant. Do not count points on a line.
•Add the diagonally opposite quadrants. Find the smaller sum and the total of points in all
quadrants.
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N=A+B
• Look up the limit for N on the trend test table. (next page)
If Q is less than the limit, the two variables are related.
If Q is greater than or equal to the limit, the pattern could have occurred from
random chance.
37. MANUAL METHOD
OPTIONAL. USE
Basic Quality Tool No 5 : Scatter Diagram EXCEL TEMPLATE
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Scatter plot
Q = the smaller of A and B
N=A+B
Next, with the N, look up Trend Test table
to find Limit for that N
• If Q is less than the limit, the two
variables are related.
• If Q is greater than or equal to the
limit, the pattern could have occurred
from random chance.
38. Basic Quality Tool No 5 : Example of Scatter Diagram
OPTIONAL.
The ZZ-400 manufacturing team suspects a relationship between product
purity (percent purity) and the amount of iron (measured in parts per million or
ppm).
Purity and iron are plotted against each other as a scatter diagram, as shown in
the figure below.
There are 24 data points.
Median lines are drawn so that 12 points fall on each side for both percent
purity and ppm iron.
39. Basic Quality Tool No 5 : Example of Scatter Diagram
MANUAL METHOD OPTIONAL. USE EXCEL
TEMPLATE
To test for a relationship, we calculate:
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
Then we look up the limit for N on the trend test table.
For N = 24, the limit is 6.
(See red circle on the Trend Test table - 2 pages before)
Q , which is 6, is equal to the limit, which is also 6.
Therefore, the pattern could have occurred from
random chance,
and no relationship is demonstrated.
40. Basic Quality Tool No 6 : Stratification (Categorization)
Description
Stratification is a technique used in combination with other data analysis tools.
When data from a variety of sources or categories have been lumped together,
the meaning of the data can be impossible to see. This technique separates the
data so that patterns can be seen.
When to Use Stratification
• Before collecting data.
• When data come from several sources or conditions, such as shifts, days of
the week, suppliers or population groups.
• When data analysis may require separating different sources or conditions.
41. Basic Quality Tool No 6 : Stratification
(CATEGORIZATION OF DATA)
Stratification Procedure
•Before collecting data, consider which information about the sources of the
data might have an effect on the results. Set up the data collection so that you
collect that information as well.
•When plotting or graphing the collected data on a scatter diagram, control
chart, histogram or other analysis tool, use different marks or colors to
distinguish data from various sources.
• Analyze the subsets of stratified data separately.
•Data that are distinguished in this way are said to be “stratified.”
42. Example of Stratification – We want to reduce number
of complaints but looking at the data by Region
Count of Case Description
RD (Region) Total Number of Complaints
1 118
2 137 • Analyze the subsets of
3 47 stratified data (category)
4 68
separately. In this case, it’s
5 42
recommended to look at the
6 49
7 15
problem region by region.
8 18
9 20
(blank)
Grand Total 514
43. Basic Quality Tool No 7 : Control Chart
Also called: statistical process control (SPC)
Description
•The control chart is a graph used to study how a process changes over time.
Data are plotted in time order.
•A control chart always has a central line for the average, an upper line for the
upper control limit and a lower line for the lower control limit.
•These lines are determined from historical data.
•By comparing current data to these lines, you can draw conclusions about
whether the process variation is consistent (in control) or is unpredictable (out
of control, affected by special causes of variation).
44. Basic Quality Tool No 7 : Control Chart
When to Use a Control Chart
•When controlling ongoing processes by finding and correcting problems as
they occur.
•When predicting the expected range of outcomes from a process.
•When determining whether a process is stable (in statistical control).
•When analyzing patterns of process variation from special causes (non-
routine events) or common causes (built into the process).
•When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process.
45. Basic Quality Tool No 7 : Control Chart Double Click on file to
construct Control Chart
Control Chart Basic Procedure
• Choose the appropriate control chart for your data.
• Determine the appropriate time period for collecting and plotting data.
• Collect data, construct your chart and analyze the data.
Microsoft Office
• Look for “out-of-control signals” on the control chart. When one is identified, Worksheet
Excel 97-2003
mark it on the chart and investigate the cause.
• Document how you investigated, what you learned, the cause and how it was
corrected.
OPTIONAL TO MEMORIZE .. USE EXCEL TEMPLATE AND
Out-of-control signals CHEECK INDICATORS
•A single point outside the control limits. In Figure 1, point sixteen is above the UCL (upper
control limit).
•Two out of three successive points are on the same side of the centerline and farther than 2 σ
from it. In Figure 1, point 4 sends that signal.
•Four out of five successive points are on the same side of the centerline and farther than 1 σ
from it. In Figure 1, point 11 sends that signal.
•A run of eight in a row are on the same side of the centerline. Or 10 out of 11, 12 out of 14 or 16
out of 20. In Figure 1, point 21 is eighth in a row above the centerline.
•Obvious consistent or persistent patterns that suggest something unusual about your data and
your process.
46. Basic Quality Tool No 7 : Control Chart
•Continue to plot data as they are generated. As each new data point is plotted,
check for new out-of-control signals.
•When you start a new control chart, the process may be out of control. If so, the
control limits calculated from the first 20 points are conditional limits.
•When you have at least 20 sequential points from a period when the process is
operating in control, recalculate control limits.
49. References
Principles of Quality Costs: Principles, Implementation, and Use, Third Edition, ed. Jack
Campanella, ASQ Quality Press, 1999, pages 3-5.
Duke Okes and Russell T. Westcott, Certified Quality Manager Handbook:
Second Edition, ASQ Quality Press, 2001, pages 245-246.
G. Dennis Beecroft, Grace L. Duffy, and John W. Moran,
The Executive Guide to Improvement and Change, ASQ Quality Press, 2003,
pages 17-19
Nancy R. Tague’s The Quality Toolbox, Second Edition, ASQ Quality Press,
2004