To illustrate we'll create a chart with the underlying spreadsheet data shown in exhibit 2, below.
Click on Insert on the toolbar, then Chart to bring up the Chart Wizard (exhibit 3, below).
In other words, the X chart measures the batch-to-batch variation, while the R chart measures the variation within each batch.
These depend on the number of samples you take for each point on the chart (more detail will be foundin books and manuals on SPC), but for three samples per point, a good approximation is:
You can, of course, substitute any Wingdings character you like for the n in the formulas to produce a different image in the chart.
Also known as a time and activity chart, the Gantt chart displays a timeline for each task and is an effective way to keep a project on schedule.
Most SPC software programs only have median chart factors for sample sizes up to 10, which limits their use for higher-cavitation molds, according to van der Veen.
Evaluation using the M/I chart revealed two things: changes in median weights indicated global shifts in the process; and the weight for cavity number six was consistently lower than all of the others.
With the assistance of the [X-bar] chart, an otherwise unseen problem was detected and eliminated.
The R chart shows the daily range of values compared to the UCL and average lines.
This Windows-based software includes "brainstorming" sections, cause-and-effect diagramming, data collection, flow charting, and various other charting capabilities - including Pareto charts
, scatter diagrams, and box plots.