TABLE OF CONTENTS I realize that this upper case Greek letter sigma, ?, means 'some of', but how do I know which ones to choose?
Undergraduate at a British University
Inferential statistics is about drawing conclusions about a body of data on the basis of taking a representative sample. As such it forms an important aspect of Six Sigma activities. This concept is illustrated as a process in Figure 8.1.
In Figure 8.1, a population refers to the totality of items or entities under consideration. [A]: It is statistical convention to symbolize a population parameter by lower case Greek letters in italics. For example, mean = ( mu); standard deviation = ? ( sigma). [B]: A population parameter is deduced from a sample statistic. It is statistical convention to symbolize a sample statistic by upper case Latin letters in italics. For example, mean = X; standard deviation = S. [C]: It is statistical convention to symbolize a realized value of a sample statistic by lower case Latin letters in italics. For example, mean, x = 12.0; standard deviation, s = 1.0.
Of particular relevance to Six Sigma practitioners is the use of the sigma symbol as a measure of standard devation. This is because the Six Sigma 'Sigma' means something quite different. This sigma situation is compounded by two further aspects. First, the Six Sigma 'Sigma' is related in a peculiar and arbitrary way to...
