Statistical Quality Control (SQC) is the term used to describe the set of statistical tools used by quality professionals.

1. Prepared By:
Foram Ravat
M.Pharm (QA)
Graduate School of Pharmacy
Gujarat Technological University
Enrollment no :192880824011
Guided by :
Dr Kashyap N Thummar
M.Pharm , PGDIM, PhD
Assistant Professor
Graduate school of Pharmacy
Gujarat Technological University
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2. 2

3. Content
Statistical process control
Process Capability
The Cpk capability index
Pursuit of decrease process variability
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4. Statistical process control[1]
Statistic Process Control:
Statistics: It is branch of mathematics concerned
with collecting, organizing, and interpreting data.
Process: Combination of people, materials,
methods, machines, environment and
measurement to produce a goods or services.
Control: System/Procedure policy to achieve
results that confirms to requirements.
4

5. understanding the specification
Customer Requirement Specification
International
tennis
fedaration
(ITF)
For upcoming
Grand stam
taurnaments ITF
has engaged your
campany as one
of its suppliers
Diameter of
ball should be
between 6.56
to 6.86 cm
5

6. Cont....
6

7. Process capability[1]
In planning the quality aspects of operations,
nothing is more than advance assurance that the
processes will meet the specifications.
In recent decades, concept of process capability has
emerged to provide a quantified prediction of
process adequacy.
This ability to predict quantitatively has resulted in
widespread adoption of the concept as a major
element of quality planning.
 Process capability is the measured, inherent
Variation of the product turned out by a process. 7

8. Basic definitions[1]
Process refers to some unique combination of machine,
tools, methods, materials, and people engaged in
production. It is often feasible and illuminating to
separate and quantify the effect of the variables entering
this combination.
Capability refers to an ability, based on tested
performance, to achieve measurable results.
Measured capability refers to the fact that process
capability is quantified from data that, in turn, are the
results of measurement of work performed by the
process.
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9. Uses of process capability information[1]
Process capability information serves multiple
processes:
Prediction the extent of variability that processes will
exhibit. Such capability information, when provided
to designer, provides important information in setting
specification limits.
Choosing from among competing processes that are
most appropriate to meet the tolerances.
Planning the interrelationship of sequential
processes.
For example, one process may distort the precision
achieved by a predecessor process, as in hardening
of gear teeth. Quantifying the respective process
capabilities often points the way to a solution. 9

10. Cont.....
Providing a quantified basis for establishing a
schedule of periodic process control check and
readjustments.
Assigning machines to classes of work for which
they are best suited.
Testing theories of causes of defects during
quality improvement programs.
Serving as a basis for specifying the quality
performance requirement for purchased machines.
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11. Standardized Process Capability Formula[1]
The most widely adopted formula for process
capability is:
Process Capability= ±3σ (a total of 6σ)
Where σ is the standard deviation of the process
under a state of statistical control (i.e., under no drift
and no sudden changes). If the process is centered at
the nominal specification and follows a normal
probability distribution, 99.73 percent of production
will fall within 3σ of the nominal specification. 11

12. Relationship to product specifications[1]
A major reason for quantifying process capability is
to compute the ability of the process to hold product
specifications.
Planners try to select processes with the 6s process
capability well within the specification width. A
measure of this relationship is the capability ratio:
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13. Cont....
Where, USL is the upper specification limit and
LSL is the lower specification limit.
Note that 6s is used as an estimate of 6σ.
Some companies define the ration as the
reciprocal.
Some industries now express defect rates in terms
of parts per million.
 A defect rate of one part per million requires a
capability ratio (specification range over process
capability) of about 1.63.
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14. Four example of process vairaibility[1]
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15. Cont....
Table shows selected capability ratios and the
corresponding level of defects, assuming that the
process average is midway between the
specification limits.
 A process that is just meeting specification limit
(specification range ±3σ) has a Cp of 1.0.
 The critically of many applications and the
reality that the process average will not remain at
the midpoint of the specification range suggest
that Cp should be at least 1.33.
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16. Cont....
Process Capability Index (Cp) Total Product Outside two
sided specification limit
0.5 13.36%
0.67 4.55 %
1 0.3 %
1.33 64 ppm
1.63 1 ppm
2 0
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17. The Cpk capability index[1]
 process, as measured by refer to the variation in a
process about the average value.
This concept is illustrated in figure the two
processes have equal capabilities because 6 σ the
same for each distribution, as indicated by the
width of the distribution curves.
The process aimed at µ2 is producing defective
because the aim is off centre,not because of the
inherent variation about the aim(i.e, the
capability).
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18. Process with equal process capability width
but different aim
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19. Cont....
The index measures potential limits and the process
is operating in to have a capability index that
reflects both variation and location of process
average.
Such an index is Cpk .
Reflects the current process means proximity either
the USL or LSL.
 Is estimated by:
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20. Cont....
 In example from Kane (1986),
USL=20 X=16
LSL =8 s=2
The standard capability ratio is estimated as
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21. Cont....
Which implies that if the process were centered
between the specification limits, then only a small
proportion (about 0.27 percent) of product would
be defective?
However, we calculated
21

22. Cont....
Which indicate that the process mean is currently
nearly the USL (NOTE that if the process were
centered at 14, the value of would be 1.0). An
acceptable process required reducing the standard
deviation and/or centering the mean.
 Also note that if the actual average is equal to
the midpoint of the specification range, then
Cpk=Cp.
The higher the value of Cp the lower amount of
product outside specification limits.
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23. Cont....
 In the certified supplier some organization uses Cpk
as one element of certification criteria. In this
application, the value of Cpk desired from supplier
can be a function of the type of the commodity
purchased
A capability index can also be calculated around a
target value rather than the actual average.
 Cpm or the tanguchi index, focus on reduction of
variation from target value rather than reduction of
variability to meet specification.
Most capability indexes assume that the quality
characteristic is normally distributed.
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24. Pursuit of decrease process variability
Process Variability Reduction
Process Variability Reduction or PVR is an
approach to reduce variation in our transactional
processes in a way that dramatically reduces the
variation in our transactional outputs.
Simple PVR Define Tools
• Customer Interview
• Process Maps
• Standard Operating Procedures/Work Instructions
• Value added Analysis
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25. Customer Interview
Important information gathering technique to
identify and understand customer needs. Able to
ask follow -up questions to gather more complete
and useful feedback.
Fasters co-operative working relationships
between customer and supplier.
Must be well planned. Remember, customers can
be internal or external.
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26. Process Map or Flowchart
Visual description of the process.
Identify the customers and suppliers.
Used to identify process measure and key
measures.
Points out discrepancies in the process.
Points out inefficiencies in the process.
Initiates standardization of procedures.
Serves as a training tool.
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27. Standard Operating Procedure (SOP)/
Work Instruction (WI)
Written document that describes a process, and
the procedure
We all agree to use to run the process and
Includes critical people, policies, procedures, and
plant.
Process maps the basic process. Process maps
main sub-processes.
Write a detailed description of the work to be
done, following the process map – All obvious
sources of variability identified on the fishbone
diagram should be addressed. Insert all
information into the SOP/WI template.
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28. Value Added Analysis
• Customer recognizes the value
• Changes the product
• Done right the first time
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29. Mesasures
Types of Measures Key
 Measures metrics describing quality of the process
output, as viewed by the customer. Tell us where we
are versus where we should be.
 Process Measures Metrics describing the inputs,
steps, and/or components of the process. Help us
determine how to get where we should be.
Cycle Time Throughput
Schedule Attainment Customer
Waste or Spoilage Time of Day
Cost Employee
Number of employees Location
Proportion defective Defects
Cycle Time Size
Schedule Attainment Throughput
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30. Measure Tools
Average or Mean - Tells you where the process is
located.
Median - tells you where the process is located.
Range - the distance between the highest and the
lowest points.
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31. Cont....
Average or Mean
Median
This value which is equal number of values above it
and below it, when arranged in ascending /descending
order.
When n=even number
Where n=odd number
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32. Cont....
Range
The distance between maximum value and the
minimum Value. Uses only two data points and
Influenced greatly by extreme values
82%
20%
14% Range =82% -12% = 70%
16%
12% 32

33. Simple PVR Analyze Tools[2]
1. Brainstorming
2. Fishbone Diagram
3. Pareto Chart
4. Histogram
5. Run Chart
6. Check Sheet
7. Scatter Diagram
8. 5 Why’s
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34. Brainstorming
What is it?
 Brainstorming is a process in which a group quickly
generates as many ideas as it can on a particular problem
and/or subject.
 Team member think creatively.
 Focus on problem not a team member.
 Every idea is important.
Why is it useful?
 Brainstorming is useful because it can help a group of
people utilize its collective brainpower to generate many
ideas in a short period of time. It stimulates creativity and
promotes involvement and participation. 34

35. Cont....
When is it used?
To help clarify mutual expectations and devise
ground rules related to a team’s way of operating.
How is it done?
 Identify a topic, problem or issue and make sure
there is mutual understanding of the task and
objective. Write the topic on a flip chart.
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36. FISHBONE DIAGRAM
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37. Histogram
A histogram is graphic summary of variation in a set
of data. Four concepts related to variation in asset of
data underlie the usefulness of the histogram:
1. Value in set of data almost always shows variation,
2. Variation displays a pattern,
3. Patterns of variation are difficult to see in a simple
numerical tables, and
4. Patterns of variation are easier to see when the data
are summarized pictorially in histogram.
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38. Cont...
Analysis consist of identifying classifying the
pattern of variation display by the histogram (such
as the shape, the location of the center, or spread
of data from the center) the relating what know
about the characteristic pattern of physical
conditions under which the data were created to
explain what might have given rise to the pattern
in those conditions.
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39. Cont...
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40. Pareto Analysis
The tool established the priorities, dividing,
contributing effects into the “vital few” and
“useful many”.
 A Pareto diagram includes three basic elements:
1. Contributors to the total effect, ranked by the
magnitude of contribution.
2. magnitude of contribution of each expressed
numerically.
3. Cumulative percent of the total effect of the
ranked contributors.
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41. Cont...
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42. Check sheet
 Check sheet are used to collect and analyze the data.
They are type of graph or chart that is formatted to
allow immediate conclusions to be drawn regarding
the data, including patterns and trends.
 Examples: Customer service for a larger television
manufacturer noticed higher than used complaints
about falling parts on three types of television. The
repair department began a quick assessment of
television that was returned for repair. The repair
department used a check sheet to determine which
parts needed replacing and in what quantity. The
following check sheet was created for television se
models 1013, 1017, and 1019
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43. Cont....
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44. 5 why analysis
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45. Conclusion
 SPC and process capability analysis present powerful means
for the analysis of current and previous process behaviour and
they provide information that serve as a basis for the process
improvement.
 Correct implementation of SPCassures possibility to detect
special causes of process variation on time, in order to
eliminate them before generating defective products.
 Process capability analysis entails comparing the performance
of a process against its specifications, thus enabling analysis of
previous and current process performance, as well as
benchmarking.
 This is of special importance when comparing previous or
current process performance with the process performance
after improvement. 45

46. References
1. Juran’s Quality Handbook, Sixth Edition, Joseph
M.Juran and Joseph A.De Feo, ASQ Publications
page no.222, 570, 656-661.
2. Juran’s Quality Handbook, Sixth Edition, Joseph
M.Juran and Joseph A.De Feo, ASQ Publications
page no.550-667.
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