1. 7 QC TOOLS 1. Check sheet 2. Pareto Diagram 3. Cause & Effect Diagram
4. Histogram
5. Stratification
6. Scatter Diagram
7. Control Chart/
Graphs

2. Data 1. To identify problems to work on. Why Gather Data?
Facts or figures from
which conclusions can be
drawn.
A basis for reasoning,
discussion or calculation.
Data
Why Gather Data?
1. To identify problems to work on.
2. To analyze the selected problem as in
- assessing extent of problem
- identifying patterns
- verifying probable causes
3. To prevent problems from arising or
recurring.
4. To select possible action plans
5. To establish effectiveness of
implemented solutions.

3. Checksheet A check sheet is a form prepared
to facilitate checking off or marking.
The function of a check sheet is to
provide a systematic technique for
recording observations and should be designed so that
data can be posted on them and used with minimum effort.
Check sheets serve many purposes and
should be designed so data can be
posted on them and used with
minimum effort.
Checksheet
1. Agree as to what event is being observed.
2. Decide on the time period during which
data will be collected.
3. Design a form which is clear complete
and easy to use.
4. Collect data consistently and honestly.
Constructing
a checksheet

4. Pareto Diagram How to construct A Pareto Diagram is a special form of
vertical graphs which helps us to determine
which problems to solve in what order.
Doing a Pareto diagram based upon
check sheets or other forms of data
collection helps us direct our attention and
efforts to truly important problems.
Pareto
Diagram
How to construct
Step 1. Select the standard for comparison,
e.g., annual cost, frequency of defects
Step 2. Select the time period to be studied.
Step 3. Gather data. Use a checklist
Step 4. Transfer information from a check sheet
to a column graph arranged in
descending order.
Step 5. Summarize data from the check sheet
to construct the cumulative line.

5. Different Uses
1. To highlight main problems.

6. Different Uses 2. To compare problems through the
use of different measurement
scales.
Customer complaints $
loss
No.
Wrong
spec
Wrong
spec

7. Different Uses Effect Cause 3. To aid in root cause analysis
(Multi-level Pareto)
Effect Cause

8. Multi Level Pareto Illustration
1ST LEVEL
2ND LEVEL

9. Multi Level Pareto Illustration
3RD LEVEL
4TH LEVEL

10. Multi Level Pareto Illustration
5TH LEVEL

11. Different Uses 4. To evaluate before and after corrective action.
Effective

12. Problem, Effect or Result
Cause and Effect Diagram
A cause and effect diagram is a picture
composed of lines and arrows to represent
relationships between effects and its causes.
A primary use for Cause and Effect diagrams
is to analyze existing problems or situations so
that corrective measures can be taken.
The Cause and Effect diagram is a valuable
too to use in sorting out “non-contributing”
causes; leaving only the “true” causes.
How to construct
Step 1. Pick a result, effect or problem to
be solved. Virtually display problem
statement.
Problem, Effect or Result

13. Problem, Effect or Result
How to construct Cause & Effect Diagram
Step 2. Categorize causes by major elements
and put boxes around them.
Start with 4Ms and 1E (Man, Machine,
Materials, Method, Environment)
Machine
Man
Problem, Effect or Result
Method
Materials
Environment

14. Problem, Effect or Result
How to Construct a Cause & Effect Diagram
Step 2. Categorize causes by major elements
and put boxes around them.
Start with 4Ms and 1E (Man, Machine,
Materials, Method, Environment)
Problem, Effect or Result
Man
Machine
Method
Materials
Environment

15. Problem, Effect or Result
How to Construct a Cause & Effect Diagram
Step 2. Add smaller branches to main causes
and continue adding until all possible
causes are exhausted.
Problem, Effect or Result
Use brainstorming to generate a large number of specific
causes in each category.
Ask who, why, what, when, where, or how to stimulate
thinking.

16. Brainstorming It is a creative process for generating a large
quantity of ideas utilizing a group.

17. How to Use a Cause and Effect Diagram
Step 1.
Compare all causes (What is)
against operational standard
(What should be).
Circle the causes for causing
“bad” effect.
The diagram can be used to
evaluate if operational standard
is inadequate.

18. How to Use a Cause and Effect Diagram
Find out which of the circled
causes have a significant
effect on the problem.
How?
1. Use technical knowledge
2. Obtain opinion
3. Verify through data
gathering
4. Do more analysis of data
5. Possibly design an
experiment
Step 2.

19. How to Use a Cause and Effect Diagram
Steps
3. Construct a plan on how the
problems are to be resolved.
* the plan should include activities,
timetable and person responsible.
4. Because the Cause & Effect diagram
reflects graphically the results of
investigating a problem, it is a
good idea to post it in the work
area so that everyone can see
why action is necessary.
5. Continue improvements and revisions
to improvements.
3,4 & 5

20. Histogram A Histogram is a graph which shows
the frequency of occurrence in a
number of related measurements.
A histogram reveals how measurements
vary from one another and displays
the distribution of data. It can be
used to compare sample results with
specification.

21. How to Construct a Histogram
Step 1. Gather data. Minimum of 50 observations.

22. How to Construct a Histogram
Step 2. Identify the largest and smallest
measurement. Compute the range.
Range = Maximum - Minimum
reading reading
Range =
= .08

23. How to Construct a Histogram
Step 3. Determine how many classes are
required to make a histogram.
Compute for the class interval. R
Class Interval = = K
Class Interval = or .02
K is a constant determined from a table.

24. How to Construct a Histogram
For Constant K,
DATA and Class Amounts
Number of Appropriate No.
Observations of Classes
Over

25. How to Construct a Histogram
Step 4. Determine the boundary line between
classes.
Class Class Interval

26. How to Construct a Histogram
Step 5. Transfer data to a tally sheet
Tally Sheet

27. How to Construct a Histogram
Step 6. Transform data from tally sheet
to a Histogram.

28. Scatter Diagram A Scatter Diagram is used to study the
possible relationships between one variable
and another.
The Scatter Diagram is used to test for
possible cause and effect relationships.
It cannot prove that one variable causes
the other, but it does make it clear
whether a relationship exists and the
strength of that relationship.

29. Scatter Diagram A Scatter Diagram is set up whereby the horizontal
axis (X-axis) represents the measurement values of
one variable and the vertical axis (Y-axis) represents
the measurement of the second variable.
Variable 2
Variable 1

30. How to Construct a Scatter Diagram
Step 1. Collect 50 to paired samples
of data that you think may be
related. Construct a data sheet
as follows:
Relationship between Manual & Auto Titration (Sn + 2)

31. How to Construct a Scatter Diagram
Step 2. Draw the horizontal and Vertical Axes
of the diagram. 50 43 42 40
Auto g/l y
Manual g/l X

32. How to Construct a Scatter Diagram
Step 3. Plot the data on the diagram. If you
find the values being repeated, circle
that point as many times as appropriate.

33. Scatter Diagram Patterns Positively Correlated Negatively Correlated
No Correlation

34. Stratification Helps analyze cases in which data
Stratification is a process of classifying
data into subgroups based on categories
and characteristics.
Helps analyze cases in which data
actually masks the real facts.
Breaks down single numbers into
meaningful categories or classifications
to focus on the corrective action.

35. When to Stratify? 1. During data gathering to design check
sheets, create checklist, scatter diagram
and cause and effect diagram.
2. During data analysis when using histograms,
pareto charts, scatter diagrams and
cause and effect analysis.
Stratification break down single numbers into
meaningful categories or classifications to focus
on corrective action.

36. What is a Control Chart? Control Chart is a graphic representation of
a process.
Sample averages are plotted on the chart.
Statistically determine the upper and lower
control limits drawn on either side of the
process average.
Makes it possible to tell if a process is functioning normally
and to see immediately if malfunctioning has occurred.