03/10/2003 Week #3 江支弘 Chapter Three Statistical Process Control

03/10/2003 Week #3 江支弘 QUALITY IMPROVEMENT AND STATISTICS 品質改善與統計 quality improvement statistical quality control fitness for use quality of design quality of conformance reduction of variability elimination of defects elimination of waste

03/10/2003 Week #3 江支弘 Control Chart 品質管制圖 Monitor a production process or an operation Predetermined control limits Assignable causes, e.g. machinery, operator, raw materials, or environmental disturbance

03/10/2003 Week #3 江支弘 Sampling Distributions 取樣分佈 Frequency curve for sample mean Bell shape, regardless of the shape of the parent population’s frequency curve Central value μ 與母體相同 Less variation  standard error of sample mean

03/10/2003 Week #3 江支弘

03/10/2003 Week #3 江支弘 Normal density curves 常態密度曲線 Symmetric and bell-shaped 鐘型 ( 鈴鐺形 ) 鈴鐺形 Can be completely described by mean and standard deviation Mean  center of the distribution, center of symmetry Standard deviation  shape of the curve, distance from mean to change-of-curvature points on either side

03/10/2003 Week #3 江支弘 Mean and Standard Deviation 平均值與標準差

03/10/2003 Week #3 江支弘 Normal distributions and rule 68% of observations fall within one standard deviation, , of the mean 95%  two  ’s 99.7%  three  ’s

03/10/2003 Week #3 江支弘

03/10/2003 Week #3 江支弘 In and Out-of Control A process is in control  f3-2a out of control  f3-2b

03/10/2003 Week #3 江支弘 In Control

03/10/2003 Week #3 江支弘 Out of Control

03/10/2003 Week #3 江支弘 取樣時間的 母體特徵