Tham khảo tài liệu 'engineering statistics handbook episode 7 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | . Dex Youden plot Motivation Definitionally if a factor is unimportant the average will be approximately the same as the - average and if a factor is important the average will be considerably different from the - average. Hence a plot that compares the averages with the - averages directly seems potentially informative. From the definition above the dex Youden plot is a scatter plot with the averages on the vertical axis and the - averages on the horizontal axis. Thus unimportant factors will tend to cluster in the middle of the plot and important factors will tend to be far removed from the middle. Because of an arithmetic identity which requires that the average of any corresponding and - means must equal the grand mean all points on a dex Youden plot will lie on a -45 degree diagonal line. Or to put it another way for each factor average average - constant with constant grand mean So average constant - average - Therefore the slope of the line is -1 and all points lie on the line. Important factors will plot well-removed from the center because average average - at the center. Plot for defective springs data Applying the dex Youden plot for the defective springs data set yields the following plot. LL o 90 z tf so z Ọ s70 z o UJ 60 d LLI 0 Ề 50 IM http div898 handbook pri section5 2 of 3 5 1 2006 10 31 31 AM . Dex Youden plot How to interpret Conclusions for the defective springs data In the dex Youden plot we look for the following 1. A ranked list of factors including interactions . The intersecting dotted lines at the center of the plot are the value of the grand mean on both the vertical and horizontal axes. Scan the points along the negative-slope diagonal line and note as to whether such points are clustered around the grand mean or are displaced up or down the diagonal line. 1. Which point is farthest away from the center This defines the most important factor. 2. Which point is next farthest away from the center
