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Specialized Control Charts |
As a preliminary step in the analysis, the data are sorted
by lane and visually screened for outliers (test values
greater than 130) with box plots created as follows:
proc sort data=film; by lane;
symbol v=dot c=yellow; title 'Outlier Analysis'; proc shewhart data=film; boxchart testval*lane / boxstyle = schematicid idsymbol = dot cframe = vigb cboxfill = vlib cboxes = yellow vref = 130 vreflab = 'Outlier Cutoff' hoffset = 5 nolegend stddevs nolimits ; id sample; run;
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Figure 49.9 shows similarly created box plots
for the data in FILM after the outliers have been
removed.*
data film; set film; if testval < 130;
symbol v=dot c=yellow; title 'Variation Within Lane'; proc shewhart data=film; boxchart testval*lane / boxstyle = schematicid boxwidth = 5 idsymbol = dot cframe = vigb cboxfill = vlib cboxes = yellow hoffset = 5 nolegend stddevs nolimits ; id sample; run;
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Since you have no additional information about the process,
you may want to create a conventional and R
chart for the test values grouped by the variable SAMPLE.
This is a straightforward application of the XRCHART
statement in the SHEWHART procedure.
proc sort data=film; by sample;
symbol v=dot c=yellow; title 'Shewhart Chart for Means and Ranges'; proc shewhart data=film; xrchart testval*sample / split = '/' npanelpos = 60 limitn = 4 coutfill = red cframe = vigb cinfill = vlib cconnect = yellow nolegend alln; label testval='Average Test Value/Range'; run;The
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