Flashcards
L#10 Quality Control
Cards in this deck (24)
- 1Define each of the 5 definitions which combine to give quality, briefly explain each and give an example of each. (15)1. The transcendent approach, which views quality as meaning 'innate excellence' e.g. quality in a Rolex watch.
2. Manufacturing based quality, which views quality as being free of errors e.g. quality in a swatch watch.
3. The user based approach, which views quality as fit for purpose e.g. food or silence on a night time flight.
4. Product based approach, which views quality as a 'measurable set of characteristics' e.g. a watch that has to work for 5 years, keeping time within 5 seconds.
5. The value-based approach, which views quality as a balance between 'cost and price' e.g. value of a McDonalds meal. - 2Give a more general definition of quality. (1)Consistent conformance to customers' expectations (1)
- 3What will be an outcome of increase in quality? (1)Ultimately an increase in profits through a series of causal links (1)
- 4What is a quality gap? (1)A gap between customers' expectations and their perception of of the products/services they receive.
- 5What is diagnosing quality problems? (1)Analyzing various gaps to determine the cause for its existence (1)
- 6Describe the four types of quality gaps (4)1. The customer's specification-operation's gap.
2. The concept-specification gap.
3. The quality specification-actual quality gap
4. The actual quality-communicated quality gap. - 7Generally, which departments handle which type of quality gaps? (3)Marketing, manufacturing and product design departments generally handle gaps 1 and 2 in a joint manner.
Manufacturing handles gap 3.
Marketing handles gap 4. - 8Which quality gaps are targeted by the manufacturing department in a quality management plan? (1)Gaps 1 to 3 (1)
- 9What is the first step of a quality management plan? (6)Define the characteristics of the product. The various elements within the concept of quality for a product are identified in this step. (1) These include:
1. Functionality, or how well the product or service does its job. This includes performance and features. (1)
2. Appearance refers to the sensory characteristics of the product or service: its aesthetic appeal, look, feel, sound and smell. (1)
3. Reliability is the consistency of the product's or service's performance over time, or the average time for which it performs within its tolerated band of performance. (1)
4. Durability means the total useful life of a product or service, assuming occasional repair or modification. (1)
5. Recovery means the ease with which problems with the product or service can be rectified or resolved (1) - 10What is the second step of a quality management plan? (4)DECIDE HOW TO MEASURE EACH CHARACTERISTIC. (1) Some characteristics are easily quantifiable as continuous real numbers. These are referred to as variables. (1) Other characteristics are assessed by judgment and dichotomies (i.e. have two states, for example: right or wrong, OK or not OK). These are called attributes (1). It is imperative to choose an appropriate method of measurement for each variable and attribute as it has direct attribute as it has direct implications for quality control cost (1)
- 11What is the third step in a quality management plan? Give an example (2)For each characteristic, the acceptable level of quality needs to be defined in clear terms (e.g. 2000 hours of life for a lightbulb).
- 12What is the fourth step in a quality management plan? (1)Control the quality against the set quality standards (1)
- 13What is the fifth step in a quality management plan? (1)Find and correct sources of errors. This entails identifying operations and processes that create the error and trying to mend them.
- 14What is the sixth step in a quality management plan? (1)Continue to make improvements. Achieving better quality is a journey and not a destination. Ongoing improvement is essential for competitiveness (1)
- 15What are the three major decisions in quality control? (3)1. Where should the quality be controlled? (1)
2. Check every product or take a sample? (1)
3. How should the checks be performed? (1) - 16Give some insight into where the quality should be checked in quality control. (7)1. Checking at the start of the process could be used to inspect raw material (1)
2. Checking can take place at any time in the process, but is more desirable in specific situations (1), for example:
a. Before a costly part of the process (1)
b. Before a series of processes which are difficult to check (1)
c. Immediately before a well known fail point (1)
d. Before the process after which recovery of raw material becomes impossible. (1)
3. Checks at the end of the process can be used to ensure the quality of the product or service that is delivered to the customer (1) - 17Give 4 reasons with examples where testing every product may be impractical in quality control (4)1. It may be dangerous or impractical to check every item (1) e.g. a Doctor checking a patient's blood
2. Destructive tests are inappropriate for running on every product e.g. testing a light bulb's life (1)
3. Checking every item could be time-consuming and costly (1)
4. There may be cases when despite testing every product, reliable data cannot be gathered (e.g. detecting a disease uncertain) (1) - 18Describe in detail the Error Type 1 which must be used when sampling is used in quality control.Error 1 concerns false positives, whereby the sample indicates a positive trait in the population while the real population does not have that trait. (1)
For example: If a school inspector check the work of 20/1000 students, where all 20 in the sample have plagiarised, the inspector may draw the conclusions that all students have cheated. In fact, it was just a coincidence that the sample contained all the cheats. The inspector would be making a type I error. (1) - 19Describe in detail, with an example, a Type II error in quality control. (3)Similar principal to Type I error, basically the opposite.
If someone tests 50/1000 items and finds no problems, and assumes that the entire population has no problems. If it is the case that it is just a coincidence that those 50 did not have problems, their assumption is wrong, and they are making a Type II error. (3) - 20What are the two approaches to quality control checks? (2)1. Statistical Process Control (SPC) (1)
2. Acceptance Sampling (1) - 21Explain how SPC works. (2)1) SPC is a technique that monitors processes as they produce products or services (1) and attempts to distinguish between normal and natural variation in process performance and unusual or 'assignable' causes of variation (1)
- 22Explain how Acceptance Sampling works (3)Acceptance Sampling is a technique of quality sampling that is used is used to decide whether to accept a whole batch of products (and occasionally services) on the basis of a sample (1); it is based on the operation's willingness to risk rejecting a 'good' batch and accepting a 'bad' batch (2) (type I and II error (3)
- 23Describe in relation to statistics and numbers how SPC works. (3)1. Based on the assumption that quality variables measured on products based on normal (Gaussian) probability distributions, and modelled with normal curves (1)
2. This is a particularly good assumption if the results of the process are affected by a series of random distributions in sequence, see literature on central limit theorem (1)
3. SPC control charts work on the basis that if the output of a process is outside its natural variance, something is wrong and intervention is required (1). - 24Explain what 'Six Sigma' is. (2)1. Six Sigma is a broad 'philosophy of improvement' that adopts a specific approach for controlling, improving and managing quality. (1)
2. It is named 'Six Sigma' because it requires that the natural variation of processes (+- 3sigma) to be half of their required specification range (1).
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- Manufacturing Operations and Technology Flashcards on L#10 Quality Control, created by Block on 08/03/2014.
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