Table 2 

NO_{3}^{}/Hormone Response Interaction. 

Description of Comparison 
Coefficient Estimate 
Pvalue 


N/Hbicluster 1 vs. Exclusive +N/Hbicluster 6 
1721.4 
4.08E05 
N/HBicluster 16, 19, 20 vs. Exclusive + N/Hbicluster 6 
761.8 
0.0099 
Treated vs. Control 
1290.1 
5.82E07 
N/Hbicluster: Treated 
2190.2 
0.00022 
N/HBicluster 16, 19, 20: Treated 
1011.9 
0.01539 


Analysis of variance that examines the response to nitrate treatment of Nbicluster 9 genes that fell into various hormone biclusters or failed to appear in a hormone bicluster. Coefficients and pvalues in the simplest model that retained explanatory power. The geneexpression response variable is determined by main effects of Treatment (with 2 levels: control and treated), N/H bicluster (with 3 compound levels), and an interaction term between N/H bicluster and Treatment. In this model, Nbicluster 9 exclusive genes and N/H bicluster 6 genes form an aggregate "control" group with no significant difference between them. A second, significantly different, aggregate group is comprised of genes in N/Hbiclusters 16,19 and 20. A third group includes genes from N/Hbicluster 1 only. The control level for the Treatment factor is KCl. In this table each maineffect coefficient represents a difference in expression from the group comprised of Nbicluster 9 exclusive and N/H bicluster 6 genes under KCl treatment. The interaction term is over and above the main effects. For example, the difference between the mean expression of N/Hbicluster 1 genes under nitrate treatment and the mean expression of the controlgroup genes under control treatment (KCl) is obtained by summing: the main effect of N/Hbicluster 1 (1721.4); the main effect of (nitrate) Treated (761.8); and the term representing the interaction between N/Hbicluster 1 and Treated (2190.2). 

Nero et al. BMC Systems Biology 2009 3:59 doi:10.1186/17520509359 