Saving runs in fractional factorial designs

Abstract

When it is known a priori that some contrasts are negligible in a factorial design, their expressions can be used to deduce the missing results. In this article we propose a method for using this procedure when, as in the case of fractional designs, it is not known which contrasts will be null. The method is based on first establishing an interval of possible values corresponding to each of the missing results, then identifying which contrasts are always null independently of the value of said results.

Keywords:

• Factorial designs
• missing values
• negligible interactions
• saving runs
• lean designs

Additional information

Notes on contributors

Pere Grima

Pere Grima is Associate Professor of Statistics at the Universitat Politècnica de Catalunya – BarcelonaTech, where he also earned his PhD. One of the areas he specializes in is experimental design. He has more than twenty years of experience in helping companies implement statistical methods for quality control and improvement. He has been an advisor for the European Quality Award and has acted as a consultant to several multinational companies in Six Sigma projects.

Lourdes Rodero

Lourdes Rodero has a degree and a PhD in Statistics. She is an Associate Professor in the Department of Statistics and Operations Research at the Universitat Politècnica de Catalunya – BarcelonaTech. Her research is focused on Applied Statistics and Modelling for quality improvement using Six Sigma Methodology. She is also interested in Bayesian statistics and its use in design of experiments.

Xavier Tort-Martorell

Xavier Tort-Martorell is Associate Professor of Statistics at the Universitat Politècnica de Catalunya – BarcelonaTech. His research interests and industrial consulting activities cover quality management and improvement, Six Sigma, design of experiments and data-based decision making. He is currently an Associate Editor at TQM&BE (Total Quality Management & Business Excellence), QTQM (Quality Technology and Quantitative Management) and the International Journal of Quality and Service Sciences. Has been an Assessor for the European Quality Award, a jury member for the Catalan Quality Prize and President of the European Network for Business and Industrial Statistics (ENBIS) in 2012 and 2013.