TABLE V. Two-way analysis of variance (ANOVA) analysis for the application of the WHO International Biological Reference Standard (WHO/NIBSC 09/188).

Two-way ANOVA of optical density/cutoff averages (test and dilution)
WHO/NIBSC 09/188
Source of variation	SS	DF	MS	F-value	p-value
Assay kit	131.92	6	21.99	9.18	0.002
Dilution	195.27	6	32.54	13.59	0.000
Residual	86.18	36	2.39
Total	413.37	48	8.61

DF: degree of freedom; MS: medium square; SS: sum of squares.