Comparison of two ferritin assay platforms to assess their level of agreement in measuring serum and plasma ferritin levels in patients with chronic kidney disease

Table 2 Shapiro–Wilk W test for normal data

Region	Variable	N	W	V	z	p-value
TE	Abbott	111	0.943	5.10	3.64	< 0.001
TE	Ortho	111	0.936	5.72	3.89	< 0.001
CA	Abbott	68	0.966	2.02	1.53	0.062
CA	Ortho	68	0.954	2.77	2.21	0.013
Combined TE and CA	Abbott	179	0.959	5.60	3.94	< 0.001
Combined TE and CA	Ortho	179	0.949	6.89	4.414	< 0.001

TE Top End, CA Central Australia, Abbott Abbott ARCHITECT i1000 platform, Ortho Ortho Clinical Diagnostics Vitros 7600 platform, N Number of observations, W: measure of how well the ordered and standardized sample quantiles fit the standard normal quantiles. 1 is perfect match for normality. V: The median values of V should be 1 for samples from normally distributed data populations. Large values of V indicate nonnormality. P-value < 0.05 means that the hypothesis that the data is normally distributed should be rejected

ISSN: 1471-2369