FIGURE 1. Probability tree.
From the following article:
Developing and interpreting models to improve diagnostics in developing countries
Federico Girosi, Stuart S. Olmsted, Emmett Keeler, Deborah C. Hay Burgess, Yee-Wei Lim, Julia E. Aledort, Maria E. Rafael, Karen A. Ricci, Rob Boer, Lee Hilborne, Kathryn Pitkin Derose, Molly V. Shea, Christopher M Beighley, Carol A. Dahl & Jeffrey Wasserman
444, 3-8
doi:10.1038/nature05441
The population of interest is positioned at the base of the tree. The population is then split into three different access levels, depending on whether and where its members enter the health-care system. Within each access level, individuals might be tested and experience either a positive or a negative result. They are then further divided according to their disease status, and, as a result, are assigned one of the possible four test outcomes: true positive (TP), false positive (FP), true negative (TN) and false negative (FN).
