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Analysis of Unbalanced Data by Mixed Linear Models Using the mixed Procedure of the SAS System
Author(s) -
Spilke J.,
Piepho H. P.,
Hu X.
Publication year - 2005
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.2004.00120.x
Subject(s) - mixed model , computer science , representation (politics) , generalized linear mixed model , data mining , linear model , algorithm , machine learning , politics , political science , law
Unbalanced data are a common problem in plant research based on designed experiments. Such data are often conveniently analysed using linear mixed models. Recent developments in mixed model theory have been implemented in major packages. This paper describes the use of the mixed procedure of the SAS System for the analysis of designed experiments. Special emphasis is given to the specification of options as depending on the assumed mixed model and on the unbalancedness in the data. In addition, we consider a compact representation of multiple comparisons for unbalanced data (letter display). Two small data sets are used to exemplify the methods.