Conducting the Knowledge Transfer
February 12, 2025
The recent report by the World Bank about doing business in India places the country at 130 among the nearly 180 countries surveyed. India has risen by four places as compared to 2015 and other parameters in the index have improved. The change of government in 2014 which ushered in a pro business and pro-reform […]
The Game Changing and Disruptive Entry of Reliance Jio The entry of Reliance Jio into the Indian Telecom sector has been if not anything, disruptive and game changing. Starting with the sheer scale of its operations wherein it leveraged its existing network of stores and outlets to sell new connections to the consumers, to its […]
The actual work done in a Six Sigma project is done by the members involved. The Project Lead, Finance Certifier, Project Coach are all planning and enabling the team members to work in some way. Since the Project Team is usually a heterogeneous mix of people from different departments, there is no uniformity in the […]
In recent years, the term Business Process Outsourcing or BPO has gained prominence and the trend of outsourcing back office operations to centers in India and Philippines along with other countries in Asia has taken center stage. Often, we come across projections that show a greater growth in BPO with more western firms outsourcing to […]
The Chinese economic prowess is second to none. They have certainly pulled off an economic miracle since Mao Zedong began unleashing his tough policies on the people. The transformation was painful. However, as a result, China has become a global economic behemoth, a power to be feared. It is the second largest economy in the […]
Just like there are many types of discrete data charts available, there are also many types of continuous control charts available. The Six Sigma process methodology prescribes which chart must be used when. The prescription in the case of continuous data points is largely based on sample size.
Below is the list of the different control charts that need to be used for different sample sizes:
Individual Chart: In the case of an individual data chart, each observation is plotted as a separate data point. This means that there is no rational subgrouping of data. This chart must therefore be used when the sample size equals 1.
Moving Range Charts: Unlike the individual data chart, the moving range chart plots the difference between two data consecutive points. The sample size of this type of control chart is therefore 2. Here the rational subgrouping of data points is based on whether they are consecutive. The moving range data charts therefore have one less data point as compared to the individual charts.
X Bar R Chart: The X bar and R chart are used to control a process when the sample size is small and constant. This is because in small sample sizes, the range of the sample approximates the standard deviation, which would be pointless to calculate, given the small size.
The X bar and R Chart are actually two different charts, which need to be looked in tandem to understand the behaviour of a process. The X bar chart shows the average performance of the process. The R chart which plots the difference between the smallest and largest value explains the variability of the process.
X Bar S Chart: The X bar and S charts are used when the sample size used to conduct the study is large and/or variable. As in the case of X bar and R chart, X bar and S charts too have a number of values. The X bar chart ensures that the mean of the process is in control whereas the S chart monitors the standard deviation. When used in tandem, they help monitor the performance of a very large process with relative ease.
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