Capital σ is used for mathematical summation symbols, such as ∑Pi, where i= 1, 2, ..., t, which is the sum of P 1+P2+ and ...+angle. Lowercase σ is used for statistical standard deviation. ?

Both the с of Cyrillic alphabet and the S of Latin alphabet are derived from Sigma. It also means summation, which means ∑ j =1+2+3+…+n.

Extended data

For average sum and stability, there must be a specific mathematical value to quantify its stability or not. σ is a specific mathematical value used to quantify the degree of stability and instability, which is itself a concept of error analysis in statistics. It is borrowed here to indicate the quality. When applied to enterprise management, σ represents the standard deviation, and the smaller the σ value, the more stable the label quality level.

On the contrary, the greater the σ value, the more unstable the quality level is. If a company needs a stable process, it should try its best to reduce the σ value. Statistically speaking, σ value is a measure of process, and the specific calculation of σ value will be explained in the course of green belt and black belt in the future.

Every result is produced by a process. The process is repeated, but there will be some subtle differences in the output of the process, which is called fluctuation. Only by controlling the difference of these outputs and making them change within a reasonable range can the quality of products be guaranteed.

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