Process control chart 过程控制图 Assignable Graph of sample data plotted over time Cause ariation 60 UCL 40 Mean Process 20 Average ±3G 0 Random 1357911 Variation Time
0 20 40 60 1 3 5 7 9 11 X Time 0 20 40 60 1 3 5 7 9 11 X Time Graph of sample data plotted over time Assignable Cause Variation Random Variation Process Average Mean Process Control Chart 过程控制图 UCL LCL
Control limits 控制限 UCL= Process Average +3 Standard Deviations LCL= Process Average -3 Standard Deviations UCL +3σ Process Average 30 TIME
Control Limits 控制限 UCL = Process Average + 3 Standard Deviations LCL = Process Average - 3 Standard Deviations Process Average UCL LCL X + 3 - 3 TIME
Types of Error 误差类型 First Type: Belief that Observed value Represents Special Cause When in Fact it is Due to Common cause Second Type: Treating Special Cause Variation as if it is common cause Variation
Types of Error 误差类型 • First Type: Belief that Observed Value Represents Special Cause When in Fact it is Due to Common Cause • Second Type: Treating Special Cause Variation as if it is Common Cause Variation