To continue, we need to define a couple of terms. The first is a probability density function and the second is a sampling distribution.A probability density function expresses a particular function in terms of integrals. Thus for a frequency distribution smoothed (over repeated sampling) to form a curve as shown below, the area [...]
One can hardly walk into a bookstore these days without being deluged with Six Sigma volumes of one sort or the other. It seems to be an answer for every businessman’s problem from controlling quality to designing new products to guaranteeing gleeful customers. As is usually the case, with these fads, the truth [...]
Briefly, there are many ways to estimate the variation of a sample of values. One is to pull out your calculator and follow the instructions for calculating the standard deviation. Typically that is what they call σ (the instructions usually have that wrong. n-1 is used for s not σ ). That estimate is of all [...]
