1. A key factor to improving your processes with SPC is the ability to view data in histograms, control charts, Paretos, pie charts, and information screens. View charts on statistics on current sets in the set workspace or in Alarms. View historical sets in History. If you’re in an active set, click the Charts button. From Alarms, highlight a characteristic in the list and click the Select button. In History, run a query and select a retrieved set. By doing any of these, SPC opens the charts tab or charts screen for the selected set. Select the chart or information screen you want to view from the charts menu. If the product has more than one characteristic, SPC displays a list of said characteristics. Select the characteristic(s) you want to view. You are able to view more than one chart at a time by selecting multiple charts from the Charts menu. If you have multiple charts on the screen, you may want to tile or cascade them by selecting Tile Charts or Cascade Charts from the Window menu. Pressing Ctrl-A rotates selection of the currently open charts. The minimize button of a chart window reduces the chart to an icon. General preference options for viewing charts are available by selecting the Preferences menu (in SPC operator) or the View menu (in SPC Examiner) and choosing Application Options. Preference options that affect all charts are displayed in the General tab. General charting preferences are the following:
a. Color Scheme: There are two settings. Select a default color scheme for all charts.
b. Auto Refresh: Turn this on for charts to be automatically updated to reflect new data.
c. Refresh Rate: Only applicable if Auto Refresh is turned on. Enter the rate, in seconds, at which you want charts to be refreshed.
d. Move to Last Subgroup Collected on Update: This is only applicable if Auto Refresh is turned on. Check if you want the cursor to move to the last collected subgroup when charts are refreshed.
2. Preferences that affect a specific chart type are covered in the section dedicated to that type of chart. The control chart displays a point for every subgroup in the set. Depending upon how the statistical tests are configured, subgroups that fail statistical tests can be displayed in red or yellow. You can use the horizontal scroll bar or the arrow keys to scroll through all the subgroups in the set. The Home and End keys take you to the first and last subgroup on the chart. The vertical indicator line shows which subgroup is selected. Select an individual subgroup by double clicking the point on the chart, clicking the left and right arrow keys on the keyboard, or using the horizontal scroll bar. Select a range of subgroups by clicking on a subgroup and dragging the mouse. There are several options for viewing control charts. The first time you select a control chart, it uses the defaults set in the Charting Preferences dialog box. Access Charting Preferences by selecting the Preferences menu, choosing Application Options and clicking on the control chart tab. Control chart preferences include:
a. Displaying tolerance lines on the chart
b. Showing the subgroups’ distribution to the right of the chart
c. Plotting sample data on the chart
d. Showing statistics to the right of the chart
e. Showing comments
f. Showing assignable causes
g. Marking statistical test failures with Xs or arrows
h. Selecting the default scaling for the chart
i. Choosing the number of subgroups to appear on a chart at one time – you can use arrows to scroll through the chart to view all subgroups
3. When you select Show Stats, the following statistics are displayed on the right side of control charts:
a. CPK (variable data only)
b. PPK (variable data only)
c. UCL (variable data only)
d. LCL (variable data only)
e. XDBAR (variable data only)
f. RANGEBAR (variable data only)
g. P, np, u, or c Bar (attribute data only)
4. You can change preference options for the current control chart by right clicking the mouse button on the control chart (click anywhere that’s not directly on the subgroup). When you change a preference via the right click menu, SPC updates the current control chart to reflect any changes, but when you close the chart and open a new one, the new chart assumes the preferences specified in the Preferences work space.
Also see the video How Do I? - Viewing Charts for more information.
Copyright 2019 by Waypoint Global LLC