Equation 12 · Part 3 · How Advanced Semiconductor Fabrication Actually Works
Symbol σ
What this part means
σ occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Its job in the formula
σ occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Full expression→Symbol σ→Article meaning
The passage around this formula
The oldest tool for doing this is the control chart, and it works by testing a sequence of measurements against known patterns rather than against a single pass/fail threshold. The classic Western Electric decision rules flag a process as suspect if, for example, a single point lands more than three standard deviations from the target, or two of three consecutive points land beyond two standard deviations, or a long run of consecutive points falls on the same side of the target line — patterns that are each individually unlikely under normal random variation and therefore signal that something about the process, not the sample, has changed [ 10 ] . Alongside the chart sits a single summary…
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
Open the illustrated variables: a letter stands for a value guide →
See this notation across published equations →
Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.