Note that the term condition in subject-condition expression coefficient includes both the phases P1, R1, P2, R2 and the characterization of length differences above (a) and below (b) threshold, and identical (id).Voxels satisfying selected thresholds indicate the physiological interpretation of the component [10].
Since the expression coefficients can be subjected to statistical tests to indicate the physiological interpretation of the component we used unpaired, two-tailed t-tests on these coefficients to identify PCs that were differentially expressed between healthy controls and PD patients (significance level p < 0.05).
The interpretation of the components has been facilitated by the application of the varimax rotation to the component matrix.
The method is described in four steps: the accuracy of image acquisition, representation of the object outline, calculation of components and interpretation of the components, all focusing on colloidal food system applications.
In this paper we study the physical interpretation of the components of the logarithmic strain tensor in any arbitrary system of representation, which is crucial in formulating meaningful constitutive models.
Search & retrieval methods not only try to identify most similar reference group, a task of traditional classifiers like nearest-neighbor (NN) [ 25, 26] and support vector machines (SVM) [ 27- 29], but also to provide interpretation of the component-wise (e.g. gene-by-gene) contributions to the similarity match.
The oblique rotation resulted in the same grouping of variables as the Varimax rotation and did not affect the interpretation of the components.
In order to provide a neurophysiological interpretation of the components, statistical tests, e.g. unpaired t-tests and tests of correlation (Pearson) were applied to the expression coefficients.
Birth weight and arm circumference have high correlations (r > 0.5) with both components in the boys and girls analyses and this fits in with our interpretation of the components as they are measurements of both skeletal size and fat.
However, we have to be cautious with the interpretation of these component maps because of the way that STEM data is recorded.
The PCA was carried out using the Factor Analysis function in Systat (ver. 13.0, released 2009), which also included selection of a Varimax rotation to improve interpretation of the principal component axes.
