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Geoff Vining’s Current Research Interest. Background. Industrial Split-Plot Experiments Important in Industry Significant Differences from Agricultural Split-Plot Experiments Hot Area in Industrial Statistics since Late 1990s. Background. What is a split-plot experiment?
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Background • Industrial Split-Plot Experiments • Important in Industry • Significant Differences from Agricultural Split-Plot Experiments • Hot Area in Industrial Statistics since Late 1990s
Background What is a split-plot experiment? • Experimental unit for some subset of factors is an observation unit for another subset of factors • Originated in agriculture
Background Pencil Lead Response: Strength • Z1-Furnace Temp (Hard-to-Change) • X1-Type of Graphite (Easy-to-Change) • X2-Grinding Method (Easy-to-Change)
Background Z1=-1 Z2=1 X1=-1 X2=-1 X1=1 X2=-1 X1=-1 X2=1 X1=1 X2=1 X1=-1 X2=-1 X1=1 X2=-1 X1=-1 X2=1 X1=1 x2=1
Background • Some factors have more experimental units than others • Consequence: Some factors have more information than others • Multiple error terms!
Second Order Designs • Let m be the number of whole plots. • Let ni be the number of subplots within the ith whole plot. • For a balanced design, ni = n for all the whole plots. • Let N be the total number of subplots.
Second Order Designs Model
Second Order Designs The variance matrix for the estimated coefficients is:
My Current Work • Kowalski, Cornell, Vining (Technometrics, 2002) • Extends split-plot structure to mixture component – process factor experiments • Proposes a pure-error basis for estimating variance components • Assumes GLS to estimate the model
My Current Work By accident, discovered a modification of a CCD attained OLS-GLS equivalence Vining, Kowalski, Montgomery (JQT 2005) Balanced Designs Allows Pure Error Estimates of Var Comp Show General Conditions Examples of CCD and Box-Behnken Recently Won the Lloyd Nelson Award
My Current Work OLS-GLS Equivalence is Nice: • Estimates do not depend on the unknown variance components • Estimates are BLUE • Properties of the estimates do not rely on asymptotics
My Current Work OLS-GLS Equivalence if there exists a non-singular matrix F such that
My Current Work • Parker, Kowalski, Vining (submitted to Technometrics) • Extends VKM for the balanced case • Develops “minimum whole plot” designs • QREI (2006) outlines catalog of designs • Parker, Kowalski, Vining (submitted to JQT) • Unbalanced Case
My Current Work • Key to Pete’s Work:
My Current Work A Design is OLS-GLS equivalent if
My Current Work • Vining and Kowalski (submitted to JQT) • Develops exact tests for OLS-GLS equivalent designs • Establishes proper residuals for diagnostic plots
My Current Work • Li Wang (current Ph.D. student) • Box and Hunter (Annals 1957) for split-plot designs • Recommendations for axial runs • “partial rotatability” • Orthogonal Blocking