Chemistry Perspective on Six Sigma concept of Normal Distribution ad Confidence interval

http://www.chem1.com/acad/webtext/matmeasure/mm5.html

Very well written and clear account of how Normal distribution and Confidence Intervals are used for making decisions.

Here is a sample:

3  Using statistical tests to make decisions

Once we have obtained enough information on a given sample to evaluate parameters such as means and standard deviations, we are often faced with the necessity of comparing that sample (or the population it represents) with another sample or with some kind of a standard. The following sections paraphrase some of the typical questions that can be decided by statistical tests based on the quantities we have defined above. It is important to understand, however, that because we are treating the questions statistically, we can only answer them in terms of statistics— that is, to a given confidence level.

The usual approach is to begin by assuming that the answer to any of the questions given below is “no” (this is called the null hypothesis), and then use the appropriate statistical test to judge the validity of this hypothesis to the desired confidence level.

The Old Man With a Hammer

A large ship engine failed. The ship's owners tried one expert after another, but none of them could figure but how to fix the engine.

Then they brought in an old man who had been fixing ships since he was a young. He carried a large bag of tools with him, and when he arrived, he immediately went to work. He inspected the engine very carefully, top to bottom.

Two of the ship's owners were there, watching this man, hoping he would know what to do. After looking things over, the old man reached into his bag and pulled out a small hammer. He gently tapped something. Instantly, the engine lurched into life. He carefully put his hammer away. The engine was fixed!

A week later, the owners received a bill from the old man for ten thousand dollars.

"What?!" the owners exclaimed. "He hardly did anything!”

So they wrote the old man a note saying, "Please send us an itemized bill."

The man sent a bill that read:

Tapping with a hammer..............................$ 2.00

Knowing where to tap................................$ 9,998.00

=========================================

If you're trying to improve your processes, like the old man you got to know where to "Tap." Effort is important, but knowing where to apply the effort makes all the difference!

I've worked with many managers that had extensive knowledge and experience however were poor at knowing where and when to focus in order to make the biggest impact for improvement.  They just didn't know where to "Tap" !

At our Lean Six Sigma Training classes you learn the methods, tools and techniques of process improvement as well as where and when to use them for maximum impact.‎..knowing where to Tap!

This 2 day tunnel project in Holland ( A12 between Ede and Bennekom) is a wonderful example of Lean Six Sigma principles in action.  See full 2 day Time-Lapse video here : www.youtube.com/watch?v=DEa9jrkQm0c
1. Identify and remove every kind of non-value-added activity ( rework, waiting, transport, motion etc ) and focus on delivery of the value ( a new passage under the main road ) as quickly as possible and minimal stress/ disruption to customers ( road users).
2. SMED/ Rapid change over. Pre-construction of as much as possible before you shut down the road ( flow of value ).   Most efficient use of time and resources while the road is closed. Every minute used...even when it rains!
3. Create FLOW in the work place. Watch how everything flows. No waiting or bottlenecks. The project managers have done an excellent job in understanding critical path and CRITICAL CHAIN of resources needed for the project (and using TOC) .
They ultimately delivered the VALUE ( a passage to drive under the highway) with high Quality, minimum time, minimum disruption...and the cost of this project was also substantially lower than equivalent projects using other traditional methods and management where delays / rework and waste push up the costs.
Congratulations to the Wagemaker engineering company in Holland ! I hope that Governments all over the world will see this video and understand what can be achieved if they change their way of thinking and apply Lean Six Sigma principles, tools and techniques to their projects.