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2.
Measurement Process Characterization
2.6. Case studies 2.6.2. Check standard for resistivity measurements
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| Histogram for check standard #137 to test assumption of normality |
reset data reset plot control reset i/o dimension 30 columns skip 25 read mpc62.dat crystal wafer mo day hour min op hum probe temp y sw df histogram y |
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| Normal probability plot for check standard #137 to test assumption of normality |
reset data reset plot control reset i/o dimension 30 columns skip 50 read mpc62.dat crystal wafer mo day hour min op hum probe temp y sw df skip 0 normal probabilty plot y |
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| Control chart for precision of probe #2372 and computation of control parameter estimates |
reset data reset plot control reset i/o dimension 30 columns skip 50 read mpc62.dat crystal wafer mo day hour min op hum probe temp y sw df skip 0 let time = mo +(day-1)/31. let s = sw*sw let spool = mean s let spool = spool**.5 print spool let f = fppf(.95, 5, 125) let ucl = spool*(f)**.5 print ucl title Control chart for precision characters blank blank O lines solid dashed blank y1label ohm.cm x1label Time in days x2label Standard deviations with probe #2362 x3label 5% upper control limit let center = sw - sw + spool let cl = sw - sw + ucl plot center cl sw vs time |
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| Shewhart control chart for check standard #137 with computation of control chart parameters |
reset data reset plot control reset i/o dimension 30 columns skip 50 read mpc62.dat crystal wafer mo day hour min op hum probe temp y sw df skip 0 let time = mo +(day-1)/31. let avg = mean y let sprocess = standard deviation y let ucl = avg + 2*sprocess let lcl = avg - 2*sprocess print avg print sprocess print ucl lcl title Shewhart control chart characters O blank blank blank lines blank dashed solid dashed y1label ohm.cm x1label Time in days x2label Check standard 137 with probe 2362 x3label 2-sigma control limits let ybar = y - y + avg let lc1 = y - y + lcl let lc2 = y - y + ucl plot y lc1 ybar lc2 vs time |
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