Quality and Reliability Methods - SAS

Chapter 2 Statistical Control Charts 35
Display Options
different options that are discussed in “Cumulative Sum Control Charts” on page 95.
Box Plots superimposes box plots on the subgroup means plotted in a Mean chart. The box plot shows
the subgroup maximum, minimum, 75th percentile, 25th percentile, and median. Markers for
subgroup means show unless you deselect the Show Points option. The control limits displayed apply
only to the subgroup mean. The Box Plots option is available only for X -charts. It is most appropriate
for larger subgroup sample sizes (more than 10 samples in a subgroup).
Needle
connects plotted points to the center line with a vertical line segment.
Connect Points
toggles between connecting and not connecting the points.
Show Points toggles between showing and not showing the points representing summary statistics.
Initially, the points show. You can use this option to suppress the markers denoting subgroup means
when the Box Plots option is in effect.
Connect Color displays the JMP color palette for you to choose the color of the line segments used to
connect points.
Center Line Color displays the JMP color palette for you to choose the color of the line segments used to
draw the center line.
Limits Color displays the JMP color palette for you to choose the color of the line segments used in the
upper and lower limits lines.
Line Width
allows you to pick the width of the control lines. Options are Thin, Medium, or Thick.
Point Marker
allows you to pick the marker used on the chart.
Show Center Line initially displays the center line in green. Deselecting Show Center Line removes the
center line and its legend from the chart.
Show Control Limits
legends.
toggles between showing and not showing the chart control limits and their
Tests shows a submenu that enables you to choose which tests to mark on the chart when the test is
positive. Tests apply only for charts whose limits are 3σ limits. Tests 1 to 4 apply to Mean, Individual
and attribute charts. Tests 5 to 8 apply to Mean charts, Presummarize, and Individual Measurement
charts only. If tests do not apply to a chart, the Tests option is dimmed. Tests apply, but will not appear
for charts whose control limits vary due to unequal subgroup sample sizes, until the sample sizes become
equal. These special tests are also referred to as the Nelson Rules. For more information on special causes
tests, see “Tests for Special Causes” on page 39 later in this chapter.
Westgard Rules are detailed below. See the text and chart in “Westgard Rules” on page 42.
Test Beyond Limits flags as a “*” any point that is beyond the limits. This test works on all charts with
limits, regardless of the sample size being constant, and regardless of the size of k or the width of the
limits. For example, if you had unequal sample sizes, and wanted to flag any points beyond the limits of
an r-chart, you could use this command.