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Root cause analysis techniques September 28, 2007

Posted by Coolguy in Six Sigma.
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5 Why Technique

Simplest technique to indentify the root cause of a problem. You ask “Why ?” for 5 times (can vary) to get to the bottom of a problem. When you have answer to a question, you can frame the answer into another “Why” Question. Its one of the most simplest techniques to identify a root for a problem. For this technique to work, questions should be concise and focussed. Its effective for solving problems involving human factors.

Fish Bone Analysis (Ishikawa Diagram)

Can be used when you have a complex problem having multiple causes and when you need to brainstorm to identify possible causes. First step is to frame a Why question stating the problem and place it at the head. Draw a horizontal line leading to the head and vertical lines leading to the main line. Label vertical lines with categories or departments where the problem may have originated.

Some standard categories for service industries are : Policies, procedures, people and strategies.

Three steps to complete a fishbone are:

  1. Brainstorming
  2. Prioritizing
  3. Action plans

4M version of the plan has Manpower, Material, Method, Machine. 5M and E has measurement and Environment exra.

Critical To Quality (CTQ) September 28, 2007

Posted by Coolguy in Six Sigma.
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CTQ focuses on key metrics of customer satisfaction. Success or failure of a product depends on the ability of a company to identify CTQ’s and translate them into product specifications. Typically used to baseline existing products.

Development of CTQ tree involves the following steps:

  1. Identify the customer E.g: Customer at fast food chain
  2. Identify Customers needs E.g: Customer is hungry and orders food
  3. Identify basic requirements of the customer E.g: Promptness of delivery, price, taste etc.
  4. Progress further with more levels as needed E.g: Taste should be good, Price economical etc.
  5. Validate the requirements with customer
  6. Translate needs into drivers for improvement
  7. Calculate measurable outcomes for improving product

CTQ Example

Customers & Quality September 28, 2007

Posted by Coolguy in Six Sigma.
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  • Customer is the ultimate judge of quality
  • Customers can be internal or external
  • Cost of acquiring new customers is typically 5-6 times more than the cost of retaining existing one
  • Only about4% of customers ever express their dissatisfaction explicitly. Rest simply switch
  • Customers may not always use the product for its intended purpose. E.g: A customer may be using PDA for only voice as the data connectivity is poor.


  • CTQ (Critical to Quality) characteristics of a product are the key quantifiable characteristics that should be met to meet customer satisfaction.
  • CTQ’s ideally have upper and lower limits and come from qualitative feedback that come from customers
  • Value-added features of a product are add-ons that may not be perceived as critical to quality.

Factors governing customer satisfaction:

  • Performance : Tyically measures in speed, accessibility, savings in cost & labor etc.
  • Features
  • Reliability : Perform at an expected level without breakdown
  • Conformance : Conform to pre-established quality standards.
  • Durability: Lenght in time a product should perfor, before it deteriorates in quality
  • Servicability: Ease, Speed and convenience of service and courtesy of service personnel
  • Aesthetics : Look & feel. Smell, sound and taste where applicable
  • Perceived value: Created in customers mind based on product desciption and advertised features.

DMAIC September 27, 2007

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Stands for:

  • Define: State the goals. Can include customer requirements, available resources, benefits, process maps etc.
  • Measure : Measure the impact t of the problem in terms of defects, missed opportunities and affected areas.
  • Analyze: Analyze the data using data analysis tools like Histograms, Pareto charts etc
  • Improve: Test various solutions to improve the root cause of the problem. Plan for full scale implementation if pilots show positive effect on the root cause.
  • Control: Create detailed control plans to maintain the levels of quality achieved in impr0ve phase. Communicate the results.

DMAIC is used when a problem can be resolved by improving and existing process or when you need a new process.

Good Problem September 27, 2007

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Characteristcs of a good problem:

  • Clearly defined
  • Impact measured in terms of time to fix and delay it causes to product delivery
  • Can be resolved by applying common quality mgmt techniques
  • Resolving the problem should have visible impact on customer satisfaction

Kano Analysis February 4, 2007

Posted by Coolguy in Business Analysis, Six Sigma.
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Kano analysis is a tool which can be used to classify and prioritize customer needs. Its named after its developer Noriaki Kano.

Kano analysis is a quality measurement tool used to prioritize customer requirements based on their impact to customer satisfaction.Kano analysis is a quality measurement tool which is used to determine which requirements are important. All identified requirements may not be of equal importance to all customers. Kano analysis can help you rank requirements for different customers to determine which have the highest priority.

This is useful because customer needs are not all of the same kind, not all have the same importance, and are different for different populations. The results can be used to prioritize your effort in satisfying different customers.

Note that the Kano model can be used to help identify customer segments, based on the relative priority of each segment’s requirements. Once segments have been defined, using both needs analysis and more tradition criteria such as gender, company size, etc., the Kano model can be re-applied to each segment to further defined the segment’s priorities.

Kano Analysis Model groups customer requirements into three basic categories:

  • Dissatisfiers ~ Basic Requirements ~ Threshold ~ “Must be’s”
  • Satisfiers ~ Variable Requirements ~ Performance ~ “More is better”
  • Delighters ~ Hidden requirements ~ Excitement

A successful product should have

  • All dissatisfiers
  • Maximum Satisfiers
  • As many delighters as possible within marketable cost of product

Dissatisfiers: Attributes of a product that customers take for granted. Customer will not buy a product if it doesn’t have this basic features. E:g Picture and sound in a TV

Satisfiers: Customers uses these to rate a product against its competition. E.g: Price of a TV

Delighters: Going beyond customer expectations. Delighters are typically provided free or with limited cost. Delighters introduce novelty to the product. E.g: A TV with games etc.