p, np Cases Are Units

  1. Select one variable containing the characteristic to be charted and move it into the Characteristic field. This variable may be numeric, string, or long string.
  2. The Value to Count group allows you to define the value to be counted and charted. If you select Nonconforming, the value specified for Value to Count represents nonconforming units. If you select Conforming, the value specified for Value to Count represents conforming units. Enter the value into the Value text box.
  3. Select one categorical variable that defines your subgroups and move it into the Subgroups Defined By field.
  4. Select one of the Charts options to choose the type of charts to generate.
    • p (Proportion of nonconforming) produces a p chart.
    • np (Number of nonconforming) produces an np chart.
  5. Click Options to specify the number of sigmas displayed on the chart and to specify the treatment of missing values in your data. Click Control Rules to specify rules for identifying out-of-control points.