Acute Mountain Sickness Symptoms Depend on Normobaric versus Hypobaric Hypoxia

Figure 2

Classification trees based on ESQ symptoms and + determination by AMS-C score in (a) all conditions combined, (b) NH, and (c) HH. CART analysis produces decision trees. The trees are created by splitting branch after branch. Branches were split based on the symptom listed at each node in the tree. The symptom was chosen by the CART analysis based on the importance of the symptom in determining AMS+. This importance is calculated using the Gini diversity index. If a subject had the symptom, he/she was placed in the right-hand branch. If the symptom was absent, he/she was placed in the left hand of the branch. If a majority of cases in a single node were AMS+, then the node was classified as AMS+. The double outlined terminal nodes indicate those classified as + based on the box plot distributions of prediction results which are under each tree. The box plots are another graphical representation of the distribution of subjects classified closer to either AMS+ or AMS−. The findings from these trees are summarized in Table 3. Imp = importance score.

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