"chips" <-
structure(list(wafer11 = c(950, 1050, 940, 990, 980, 900, 1050, 
1100, 1070, 1000, 1050, 1050, 1050, 1070, 1000, 990, 1120, 930, 
960, 970, 1100, 1040, 1030, 1030, 1010, 1000, 1100, 1030, 840, 
1040), wafer12 = c(930, 1050, 960, 1020, 980, 940, 1070, 1060, 
1030, 950, 1060, 1060, 1010, 1080, 950, 990, 1080, 950, 960, 
990, 1120, 1020, 1050, 1020, 1030, 960, 1060, 990, 850, 1060), 
    wafer13 = c(950, 1030, 940, 1020, 980, 930, 1100, 1070, 1070, 
    1010, 1040, 1060, 1080, 1070, 960, 1020, 1110, 930, 940, 
    1040, 1120, 1040, 1010, 1000, 970, 970, 1040, 1020, 830, 
    1060), wafer14 = c(930, 1040, 930, 1000, 1000, 930, 1070, 
    1050, 1020, 970, 1050, 1060, 1090, 1060, 970, 990, 1120, 
    920, 980, 1000, 1080, 1050, 1060, 1010, 1000, 960, 1080, 
    980, 850, 1070), wafer21 = c(1010, 1050, 1000, 980, 900, 
    930, 1110, 1070, 1020, 1020, 1060, 1060, 1010, 1020, 980, 
    1000, 1100, 990, 1020, 1000, 1060, 1120, 1010, 1100, 1030, 
    1090, 1020, 920, 840, 960), wafer22 = c(980, 1050, 980, 990, 
    920, 930, 1130, 1090, 1070, 980, 1030, 1070, 1040, 1020, 
    1000, 1010, 1090, 1000, 1050, 1040, 1070, 1100, 1000, 1120, 
    1110, 1120, 1000, 920, 900, 930), wafer23 = c(970, 1050, 
    960, 1000, 910, 960, 1100, 1110, 1090, 990, 1010, 1050, 980, 
    1040, 1010, 1000, 1070, 1010, 1060, 980, 1090, 1080, 1020, 
    1110, 1030, 1080, 1020, 970, 910, 950), wafer24 = c(980, 
    1060, 1020, 990, 940, 900, 1140, 1060, 1050, 1020, 980, 1060, 
    1010, 1040, 1020, 1010, 1120, 1000, 1040, 1010, 1050, 1090, 
    1030, 1080, 1060, 1100, 990, 910, 900, 980)), .Names = c("wafer11", 
"wafer12", "wafer13", "wafer14", "wafer21", "wafer22", "wafer23", 
"wafer24"), row.names = c("1", "2", "3", "4", "5", "6", "7", 
"8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", 
"19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", 
"30"), class = "data.frame")