Handbook on improving quality by analysis of process variables

EUROPEAN COMMISSION
EUROSTAT

Handbook on improving quality by analysis of process variables

Alexis Aitken, Jan Hörngren, Nia Jones, Daniel Lewis, Maria João Zilhão General Editors: Nia Jones, Daniel Lewis

Acknowledgements
Instituto Nacional de Estatística Portugal Carlos Marcelo Albano Miranda National Statistical Service of Greece Aikaterini Livaditaki Office for National StatisticsSusan Full Marta Haworth Jacqui Jones Ann Lewis Frank Nolan Bernice Reeks Andrew Stephens Nigel Stuttard Andrew Walton Helen Williams Jayne Wilson Statistiska Centralbyrån (Statistics Sweden) Leopold Granquist Reading Group for the Handbook Svein Gåsemyr Johanna Laiho Donna Livesey David Marker Hans Viggo Saebo

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Contents
1 2 INTRODUCTION TO THEHANDBOOK.................................................................................................. 4 GUIDANCE ON IMPROVING PROCESS QUALITY ............................................................................... 6 2.1 INTRODUCTION ..................................................................................................................................................... 6 2.2 MOTIVATION FOR MONITORING STATISTICALPROCESSES ..................................................................................... 6 2.3 AN APPROACH TO IDENTIFYING, MEASURING AND ANALYSING KEY VARIABLES OF STATISTICAL PROCESSES ....... 8 2.3.1 Identify Critical Product Characteristics.................................................................................................. 10 2.3.2 Develop a Process Flow Chart................................................................................................................. 11 2.3.3 Determine Key Process Variables ............................................................................................................ 12 2.3.4 Evaluate Measurement Capability............................................................................................................ 132.3.5 Determine Stability of Critical Processes ................................................................................................. 14 2.3.6 Determine System Capability.................................................................................................................... 16 2.3.7 Establish a System for Continuous Monitoring ofProcesses.................................................................... 17 2.4 REFERENCES ....................................................................................................................................................... 19 3 EXAMPLES OF IMPROVING STATISTICAL PROCESS QUALITY .................................................... 21 3.1 INTRODUCTION................................................................................................................................................... 21 3.2 THE STATISTICAL VALUE CHAIN ........................................................................................................................ 23 3.3 APPLYING QUALITY IMPROVEMENT METHODS TO STATISTICAL PROCESSES ........................................................ 26 3.3.1 DataCollection......................................................................................................................................... 30
3.3.1.1 3.3.1.2 3.3.1.3 3.3.1.4 Data Collection by Paper Self-Completion Questionnaires (ONS)........................................................................31 Face-to-face Interviewing (INE-Pt).......................................................................................................................41 Interviewing activities (SCB).................................................................................................................................55 Literature review....................................................................................................................................................66 Accessing...