质量控制表 英文版教材课程.ppt

* * * * * * * How to prepare a quality control chart ? A quality control chart is a vieual representation of confidence of intervais for a Gaussian distribution .It warns us when a monitiored property strays dengerously far from an intended target value . A control chart can show the relative deviation of calibration check samples or quality control samples from their known value.It can also display the precision of replicate analyses of unknoens or standards as a function of time. The criteria of a control chart is as following: 1 obesrvation outside the action lines 2 out of 3 consecutive measurements between warning and action lines 7 consecuitive measurements all above the enter line 6 consecuitive measurements all increasing or decreasing ,where they are located. 14 consecuitive points alternating up and down, regardless of they are located. An obvious nonrandom pattern. ( warning lines：±2σ/√n action lines： ±3σ/√n ） Volatile compounds in human blood serum were measured by GC/MS. * * * *