1. Quality planning and control
Chapter -17

2. Summary
What is quality How to diagnose quality planning and control? What are the steps to conformance to specification? Importance of statistical process control in quality planning and control. Acceptance of sampling in quality planning and control

3. What's quality ?

4. What’s quality?

5. What’s quality?

6. Quality means: Meeting specification No errors or mistakes
Good performance
Value for money
Why quality is important?
Many organizations got a dedicated dept. for quality management, which underlines the importance for quality. For example Mecedez Benz.

7. Why quality is important? Good quality reduces:
Cost
Complaints
Waste
Good quality increases:
Revenue
Satisfaction
Customers

8. High quality puts costs down and revenue up
Quality up
Image up
Processing time down
Inspection and test costs down
Rework and scrap costs down
Inventory down
Service costs down
Complaint and warranty costs down
Capital costs down
Price competition down
Sales volume up
Productivity up
Revenue up
Scale economies up
Operation costs down
The net effect of all these consequences is that revenues increase and costs reduce. In other words, the overall effect of raising quality levels is to increase profitability.
Profits up

9. What is quality in operations?
“quality is consistent conformance to customers expectations” Quality in customers view Customers expectations are based on: Past experiences Individual knowledge History Customers expectations are based on the way they perceive it. For example, one person regard car as a status symbol or luxury, where another considers as means of transport for a family.

10. The various definitions of quality or quality is the total of five approaches.
The transcendent approach views quality as synonymous with innate excellence.
The manufacturing-based approach assumes quality is all about making or providing error-free products or services.
The user-based approach assumes quality is all about providing products or services that are fit for their purpose.
The product-based approach views quality as a precise and measurable set of characteristics.
The value-based approach defines quality in terms of ‘value’.

13. Reconciling operations & customers view
Operations view- meet customers expectations
Customers view- what customer perceives
So, quality is a fit between customer expectations and customer perceptions.
For example yahoo chat and face-to-face encounter.

14. Perceived quality is governed by the gap between customers’ expectations and their perceptions of the product or service
Gap
Gap
Customers’ expectations for the product or service
Customers’ perceptions of the product or service
Customers’ expectations for the product or service
Customers’ perceptions of the product or service
Customers’ perceptions of the product or service
Customers’ expectations for the product or service
Expectations > perceptions
Expectations = perceptions
Expectations < perceptions
So the continuum between quality being perceived as poor through to it being perceived as good is primarily a function of the nature and extent of any gaps between customers’ expectations and their perceptions. The implication of this is that in order to manage customers’ perceived quality levels, both their expectations and their perceptions must be managed.
Perceived quality is poor
Perceived quality is acceptable
Perceived quality is good

15. The operation’s domain
A ‘gap’ model of quality
Management’s concept of the product or service
The customer’s domain
Previous
experience
Word-of-mouth communications
Image of product or service
Gap 4
Customer’s expectations concerning a product or service
Customer’s perceptions concerning the product or service
Gap ?
Customer’s own specification of quality
The actual product or service
Gap 1
Finally, the organization may be influencing the customers’ image of the product or service, for example through its advertising or other promotional activity, in such a way as to conflict with its actual reality. This is called gap 4.
The operation’s domain
Organization’s specification of quality
Gap 3
Gap 2

16. How to diagnose or identify quality problems?
1.Customer specification VS operation specification Gap 2.The concept vs Specification Gap 3.The quality specification gap Vs actual quality gap 4.The actual quality Vs communicated image gap

17. The perception–expectation gap
Action required to ensure high
Main organizational
perceived quality
responsibility
Ensure consistency between internal quality specification and the expectations of customers
Marketing, operations, product/service development
Gap 1
Marketing, operations, product/service development
Ensure internal specification meets its intended concept of design
Gap 2
Ensure actual product or service conforms to internally specified quality level
Gap 3
Operations
Ensure that promises made to customers concerning the product or service can really be delivered
Gap 4
Marketing

18. Conformance to specification
Conformance to specification means producing a product or providing a service to its design specifications.

19. Quality planning and control
Quality planning and control activities can be divided into six steps: 1.Define the quality characteristics of the product or service. 2.Decide how to measure each quality characteristic. 3.Set quality standards for each quality characteristic. 4.Control against these standards. 5.Find and correct causes of poor quality. 6.Continue to make improvements.

20. Define Quality characteristics
There are six quality characteristics as follows:

21. Quality characteristics of goods and services
Functionality – how well the product or service does the job for which it was intended
Appearance – the aesthetic appeal, look, feel, sound and smell of the product or service
Reliability – the consistency of performance of the product or service over time
Durability – the total useful life of the product or service
Recovery – the ease with which problems with the product or service can be rectified or resolved
Contact – the nature of the person-to-person contacts that take place

22. Decide how to measure each characteristic.
Each characteristic must be taken separately, and broken down into individual parts for measuring. For example Appearance- An appearance characteristic of a car can be spited into the color, finishing and scratches. There are two types of measures to use: Variables – something that can be measured by variable scale such as length, diameter, weight, time. Attributes – measure by judgments, such as right or wrong, ok or not ok.

23. Attribute and variable measures of quality
Attributes
Variables
Measured on a continuous scale
Defective or not defective?
Light bulb works or does not work
Diameter of bulb
Number of defects in a turbine blade
Length of bar

24. Quality of conformance
fitness for purpose
Reliability
ability to continue
working at accepted
quality level
Quality of design
degree to which
design achieves purpose
Quality of conformance
faithfulness with which the
operation agrees with design
Variables
things you can measure
Attributes
things you can assess and accept or reject

25. Step -03 Set of quality standards
When quality characteristics are measured, a quality standard is needed to check the performance.
For example one customer out of complains.
So?
Good. Because 9999 are happy.
Bad. Because many others had problem, but didn’t complaint.
Satisfactory. Because same with other companies.
In this situation, we can say quality standard is that level of quality which defines the boundary between acceptable and unacceptable.

26. Control quality against standards
After setting up appropriate standards, the operation will need to check the products or services to conform to those standards.
There are three decisions to be made:
Where in the operation should they check, that is conforming to the standards?
Should they check every single product and service or a sample.
How should the checks be performed?

27. Where should the checks take place?
There are three points where checks can be made:
At the start of process ( a placement test in the school)
During the process (before the costly part, before series of processes where checking is difficult)
After the process.

28. Check every product and service or take a sample.
Here, we decide how many of the products or services to sample.
Checking every single product is ideal, but not advisable. For example:
Doctor can’t check all the blood in a patient.
Water can’t check the satisfaction of food at every 30 seconds.
Why?
It is costly
Making difficult for employees
Sometimes customers give wrong information.(restaurant)

29. Checking sample
It saves time, but problems are many : Decision may go wrong. Type 1 and Type ii errors These are two incorrect decisions: Type 1 errors Those errors which occur when a decision was made to do something and the situation did not stop it.

30. Type 2 error
Errors occur when nothing is done yet. How should the checks be performed? In practice most operations will use some sampling. There are two sampling methods: 1.Statistical process control 2.Acceptance sampling

31. SPC or statistical process control
Sampling during the production of goods or delivery of service. Acceptance Sampling – it is a technique of quality sampling that is used to decide whether accept a whole batch of products/services on the basis of sample or not.

32. Statistical process control
Checking a product or service during the creation. If there is a reason to believe that there is a problem with the process, it can be stopped and problem can be rectified. Methods Control charts It checks the result of many samples over a period of time.

33. Process control charting
Some aspect of the performance of a process is often measured over time
Question:
“Why do we do this?”
Time
Some measure of operations performance

34. Process control charting
Some aspect of the performance of a process is often measured over time
Question:
“How do we know if the variation in process performance is ‘natural’ in terms of being a result of random causes, or is indicative of some ‘assignable’ causes in the process?”
Time
Some measure of operations performance

35. Process control charting
0.8
2.2
3.6
After the second sample
0.8
2.2
3.6
After the first sample
0.8
2.2
3.6
Fitting a normal distribution to the histogram of sampled call times
0.8
2.2
3.6
By the end of the first day
0.8
2.2
3.6
By the end of the second day

36. How can statistical process control help quality planning and control
How can statistical process control help quality planning and control? In theory if you know the specification – the characteristics to be measured and the standards to be achieved, delivering products or services to that specification should be easy. Unfortunately this is not the case. The transforming and the transformed resources are never perfect. Consider the problems that a restaurant might face:
Transforming resources
Transformed resources
The chef may be suffering from a cold or be untrained in one aspect of preparation or cooking.
Material from suppliers may be of varying quality such as interruptions to the electricity supply or bruised and rotten vegetables.
The waiting staff may be recently recruited and uncertain about their job, or they all might have been to a party the night before.
A customer may be particularly demanding or even unpleasant making it difficult for the restaurant and its staff to satisfy them.
The cleaners may not have turned up or have done a thorough job as needed to make the restaurant look clean and smart.

37. calculate the likelihood of a process being in or out of control
By checking variables and attributes managers can ensure that the service or products are being deliver to the specification. One important technique in doing this is statistical process control (SPC).
Using SPC we can:
calculate the likelihood of a process being in or out of control
set control limits based on those likelihoods
provide control charts to monitor a quality characteristic
make decisions about whether a process is in control or not and therefore whether action is needed to find and rectify a problem.

38. Variation in the process qualities
All processes vary to some extent. No machine gives precisely same result every time. Materials vary a little, the staff also vary in operation, Environment also vary. So quality also varies. These are known as common causes, and these cannot be eliminated.

39. X X X Process variability A P A P A P A P On/off target – accuracy: A
Scatter – precision: P X
A P
A P

40. Process capability
The acceptability of variation in a process. Assignable causes of variation There may be problem with process. 1.Machine damage 2. Inexperienced staff These are known as assignable variations.

41. Six Sigma approach
An approach for improvement in quality and measurement. The six sigma measuring performances. Page 567 Process control is used to control the quality.

42. Process variation and its effect on process defects per million opportunities (DPMO)
LSL
USL
LSL
USL
LSL
USL
LSL
USL
3 sigma process variation
= defects per million opportunities
4 sigma process variation
= 6200 defects per million opportunities
5 sigma process variation
= 230 defects per million opportunities
6 sigma process variation
= 3.4 defects per million opportunities

43. Acceptance sampling
The purpose of acceptance sampling is to decide whether, on the basis of a sample to accept or reject a batch. It uses the proportion of wrongs and rights. In acceptance sampling risks involved, while making judgments. Type 1 risk belongs to the producer, because the operation rejects a batch of good quality Type 2 is consumer risk because the customer accept the poor quality.

44. These risks are represented by a curve known as Operating characteristic curve.

45. How can acceptance sampling help quality planning and control?
you are an employer and you want to recruit 20 graduates it is likely that you will interview each one of them. If the batch size is large or the items of lesser value, we need a simpler, quicker and cheaper means of testing a sample to decide if the whole batch is OK or not = this is acceptance sampling. If you were the quality controller overseeing the manufacture of light bulbs it would be too time consuming to check each of the thousands made each day, and. if the check involved seeing how long they lasted it would destroy the entire output. If you were the quality controller for the marking of an A level examination, it would be impossible to check that every one of the thousands of examiners had correctly marked every one of hundreds of thousands scripts.
Using acceptance sampling we can:
decide the best size of sample to use
judge the acceptable number of defects in a batch which results in the batch being rejected for a specified level of risk
decide whether as batch should be accepted or rejected and make decisions about the action needed to find and rectify the problem.