Table 2.

Results from Principal Components Analysis of the nine principal components with eigenvalues above two, which represented pig farm biosecurity data, and logistic regression results of these components against farm-level Salmonella risk status

Component	Eigenvalue	Difference	Proportion	Cumulative	Odds ratio	P-value	95% confidence intervals
							Lower	Upper
PC1	31.22	25.329	0.312	0.312	1.095	0.005	1.028	1.167
PC2	5.89	0.124	0.059	0.371	1.070	0.420	0.908	1.259
PC3	5.77	1.409	0.058	0.429	0.831	0.028	0.704	0.980
PC4	4.36	1.088	0.044	0.472	1.008	0.943	0.821	1.236
PC5	3.27	0.272	0.033	0.505	1.227	0.121	0.947	1.590
PC6	3.00	0.499	0.030	0.535	0.762	0.008	0.623	0.932
PC7	2.50	0.209	0.025	0.560	0.930	0.578	0.720	1.201
PC8	2.29	0.143	0.023	0.583	0.912	0.457	0.715	1.163
PC9	2.15	0.173	0.022	0.604	1.033	0.805	0.796	1.341