六西格玛 六西格玛是一种旨在追求近乎完美的质量管理方法。一个以“六西格玛”水平运行的流程,其良率可达 99.9997%,这意味着其每百万次机会缺陷率 (DPMO) 仅为 3.4。该标准对应于流程中最近的规格限值与流程均值相差六个标准差的情况,这考虑到了…… 1.5σ偏移 随着时间的推移,平均值(请参阅有关有争议的 1.5 σ 偏移的具体细节,作为经验观察)。

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六西格玛 六西格玛是一种旨在追求近乎完美的质量管理方法。一个以“六西格玛”水平运行的流程,其良率可达 99.9997%,这意味着其每百万次机会缺陷率 (DPMO) 仅为 3.4。该标准对应于流程中最近的规格限值与流程均值相差六个标准差的情况,这考虑到了…… 1.5σ偏移 随着时间的推移,平均值(请参阅有关有争议的 1.5 σ 偏移的具体细节,作为经验观察)。
The core idea of Six Sigma is that a process should be so well-controlled that its output consistently meets customer requirements. Statistically, this is defined by the process capability. A process is considered capable at a six sigma level if the distance from the process mean to the nearest specification limit is at least six times the process standard deviation ([latex]\sigma[/latex]).
However, the widely cited 3.4 DPMO figure is not derived from a pure six sigma distribution. It incorporates an empirical observation that process means can drift over time. Motorola engineers observed a long-term drift of about 1.5 sigma. Therefore, the calculation for 3.4 DPMO is based on the probability of a defect when the specification limit is [latex]6\sigma – 1.5\sigma = 4.5\sigma[/latex] away from the mean. This 1.5 sigma shift is a crucial, and sometimes controversial, component of the Six Sigma methodology, distinguishing it from a purely theoretical statistical 过程控制 model. It makes the standard more attainable in real-world applications where perfect process centering is difficult to maintain over long periods.
重要提示:虽然这个目标非常接近完美,但人们不应忘记,在安全至关重要且产品或服务产量巨大的行业中,缺陷(DPMO 需要改进)可能会出现,因此需要采取潜在的综合措施和应对措施,以进一步降低或完全消除其后果。
六西格玛质量标准(3.4 DPMO)
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