Our findings were further supported by principal-component analysis, with the first factor summarizing enzyme-inducing congeners being significantly associated with neonatal TSH levels whereas the factor summarizing other congeners was not.
Table 4 shows results of the second factor analysis, and Table 5 exhibits those of the third factor analysis.
To verify the two dominant factors extracted from the third factor analysis, the fourth factor analysis using the 12 items was conducted.
Factor analysis based on 27 x 27 correlation matrix revealed that the third factor of both sexes are heterogeneous with regards to the distributions of the factor score.
The third factor analysis of the 13 items was conducted.
Exploratory factor analysis identified that all items had strong positive associations with the first factor, weak associations in most items with the second factor, and negative associations with items 13 21 (Additional file 1: Table S1).
For experiment 1, two way repeated measures ANOVAs with the first factor, tapping (synchronous, asynchronous) were used for the analysis of all conditions with only the second factor and its number of levels differing (see above).
In this study, factor analysis indicted that most of the subscales that are influenced by central vision correlated strongly with the first factor, while the 'Ocular Pain', 'Peripheral Vision', and 'Color Vision' subscales correlated strongly with the second factor.
Factor analysis indicated that the most of the subscales that are influenced by central vision and peripheral vision correlated with the first factor, while the 'Color vision', 'Ocular pain' 'Social functioning' and 'Dependency' subscales were included in the second factor.
The third factor is related to the interoperability with visual imagery and techniques for better data analysis.
A total of 39 question items covering six factors were obtained by the first factor analysis with Promax rotation.
