. 2002 Sep 27;3:27. doi: 10.1186/1471-2164-3-27

Table 4.

Concordance between pig and human hybridizations to a human nylon cDNA microarray

Comparison	Pearson^a	Spearman^b	Weighted Kappa^c
Human versus 2 μg Pig	0.93	0.93	0.76
Human versus 4 μg Pig	0.93	0.93	0.80
Human versus 6 μg Pig	0.95	0.95	0.78

^aPearson correlation coefficient assumes data are normally distributed. ^bSpearman correlation coefficient assumes data are symmetrical. ^cThe weighted Kappa statistic assumes data are ordinal. Pearson and Spearman correlation coefficients were calculated from median normalized and log transformed data. All genes were categorized according to their normalized expression level (undetectable, 0; low, 0 to 1.3; medium 1.3 to 3.0; or high, >3.0) for calculation of the weighted Kappa statistic. Results are the average of the nine pairwise comparisons among three replicates of human and three replicates of pig (2, 4, or 6 μg) skeletal muscle RNA.