Three methods for dissolving a powder in water show a different time (in minutes) it takes until the powder dissolves fully. The results are summarised in Figure 1.
There is an assumption that the population means of the three methods Method 1, Method 2 and Method 3 are not all equal (i.e., at least one method is different from the others). How can we test this?…
In some situations, Six Sigma practitioners find a Y that is discrete and Xs that are continuous. How can a regression equation be developed in these cases? Black Belt training indicated that the correct technique is something called logistic regression or binary regression. But this tool is often not well understood.…
The two-sample t-test is one of the most commonly used hypothesis tests in Data Analytics or Lean Six Sigma work. The two-sample t-test offers the statistics for comparing average of two groups and identify whether the groups are really significantly different or if the difference is due instead to random chance.…
Measurement error is unavoidable. There will always be some measurement variation that is due to the measurement system itself.
Most problematic measurement system issues come from measuring attribute data in terms that rely on human judgment such as good/bad, pass/fail, etc. This is because it is very difficult for all testers to apply the same operational definition of what is “good” and what is “bad.”…
The job of purchasing is obviously to source for reliable suppliers who deliver products conforming to specification on time within a certain price range. The more data is available about potential suppliers the better the decision will be. However, how shall the data be analysed?
FridgeMaker used to get supplies of a very crucial part, the Spacer, from Supplier X. Unfortunately, over the last months Supplier X has been struggling with waves of reorganisation resulting in unreliable deliveries and hence line stoppages for FridgeMaker.
Table 1: Supplier Qualification Data for Spacer (USL=10.8, LSL=10.2)
FridgeMaker is looking for new suppliers for all parts coming from Supplier X. Purchasing has already started the supplier qualification process for the Spacer (10.5 +/-0.3) and has received parts from suppliers A, B and C. The data are shown here. Following this data purchasing can make their decision on price. All of the suppliers meet the requirements set out in the tender document. …
“Don’t use Six Sigma to tackle special cause variation!”
is one of the common phrases being repeated by Lean Six Sigma coaches and a very important recommendation for the management, too.
The Six Sigma methodology is indeed targeting variation that is an inherent part of the process – common cause variation that has been expected and tolerated due to its unknown and supposedly complex root causes. Understanding this variation and analysing the real root causes before implementing improvements is a fundamental pillar of the methodology and driver for its success. …
Architect of High-Performing Organisations
Copyright © 2024 by COE Pte Ltd. All Rights Reserved.
