title: Analysis with respect to instrumental variables for the exploration of microarray data structures.
abstract: BACKGROUND
  Evaluating the importance of the different sources of variations is essential in microarray data experiments. Complex experimental designs generally include various factors structuring the data which should be taken into account. The objective of these experiments is the exploration of some given factors while controlling other factors.
  
  
  RESULTS
  We present here a family of methods, the analyses with respect to instrumental variables, which can be easily applied to the particular case of microarray data. An illustrative example of analysis with instrumental variables is given in the case of microarray data investigating the effect of beverage intake on peripheral blood gene expression. This approach is compared to an ANOVA-based gene-by-gene statistical method.
  
  
  CONCLUSIONS
  Instrumental variables analyses provide a simple way to control several sources of variation in a multivariate analysis of microarray data. Due to their flexibility, these methods can be associated with a large range of ordination techniques combined with one or several qualitative and/or quantitative descriptive variables.
authors.affiliation: Pulmonary Gene Research, Universitätsspital Basel, Petersgraben 4, 4031 Basel, Switzerland. florent.baty@unibas.ch
authors.forename: Florent
authors.initials: F
authors.lastname: Baty
authors.forename: Michaël
authors.initials: M
authors.lastname: Facompré
authors.forename: Jan
authors.initials: J
authors.lastname: Wiegand
authors.forename: Joseph
authors.initials: J
authors.lastname: Schwager
authors.forename: Martin H
authors.initials: MH
authors.lastname: Brutsche
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003627:Data Interpretation, Statistical; D030541:Databases, Genetic; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020869:Gene Expression Profiling / Q000295:instrumentation* / Q000379:methods*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity