G charts, like T charts, are used to plot rare events. The G chart uses the geometric distribution of the number of opportunities between events.
The data for this recipe uses the number of days between incidents at a factory. The worksheet lists this information as days until an incident has occurred. We will plot the number of days between accidents to look for unusually high or low numbers of days.
The following steps will create a G chart of the number of days between accidents at a factory:
Open the
Accidents.mtwworksheet using Open Worksheet… from the File menu.Navigate to Stat | Control Charts | Rare Event Charts and select the G… option.
Change the drop down for Form of data to Number of opportunities and the Method of counting opportunities drop down to Opportunities between events.
In the Variables: field, enter
Days.Select G Chart Options… and navigate to the Tests tab.
Select Perform all tests for special causes.
Click on OK in each dialog...