Table 1. Details of the four microarray datasets used in this research.

Study	Platform	Samples	Genes	Variables
Noordhuis et al. (2011) (GSE26511)	HG-U133_Plus_2	39	54,675	Lymph node status: negative, positive{19}
Bachtiary et al. (2006) (GSE5787)	HG-U133_Plus_2	33	54,675	Biopsy: 1{5}, 2{6}, 3{7}, 4{5}, 5{5}, 6{3}, 7{2}
Scotto et al. (2008) (GSE9750)	HG-U133A	61	22,283	tissue: normal{24}, cell line{5}, cancer{28}
Den Boon et al. (2015) (GSE63514)	HG-U133_Plus_2	130	54,675	tissue: normal{24}, CIN1 lesions{14}, CIN2 lesions{22}, CIN3 lesions{40}, cancer{28}