Figure 2.
(a) Classification and Regression Tree (CART) analysis by total intracranial volume (TICV) and diagnostic classification for females. The title of each line represents the cut-point where the model initially classifies by the Alzheimer disease (AD) diagnosis. The classification criterion is read to the left. Thus, for the first classification, TICV < 1203.8 is satisfied to the left. The numbers beneath each cut-score represent the number classified as AD for each category, read from left to right, where the first category is controls, followed by AD, vascular dementia (VaD), and mild ambiguous/mild cognitive impairment (MA/MCI), and mixed neuropsychiatric subjects. The ‘tree’ evolves as it attempts to classify by the diagnosis of AD at each ‘branch’ by TICV in the beginning of the CART analysis. In so doing the model looks at the best fit and classification rate at each branch and continues to branch until all subjects have been classified. Note that initially each heading is AD, because the model parameters for this CART analysis were based solely on TICV and AD classification until the lower branches were reached and then it classified by other diagnostic categories. (b) CART analysis by TICV and diagnostic classification for males. The decision tree is read in an identical manner as described above.