p Chart

Appendix II Attribute Charts

Lesson A2-02

Text: Appendix II pages 8 – 18

Duration: 21 minutes

Introduction and Sample Size Determination

Many people argue that tracking attribute data is inspection. However, any time we monitor statistics over time, we are implementing SPC, even if the data is attribute in type. We begin with p charts because they are commonly employed. Furthermore, percentages of scrap, absenteeism, flawed units, incorrect forms, and so on are often tracked. Although attribute data is less informative than variable type data (yes/no or counts versus actual measurement values), we can perform statistical process control on attribute data.

p Chart Control Limits and Normal Approximation

A p Chart Example

Calculate p̄

Constructing the p Chart

Download the  Calculations Worksheet for p Chart. Or view workbook page Appendix II: Page 16 and 17.