Figure 1.
A: Paths included in the baseline models. B: Paths included in the unidirectional model, in addition to all paths in baseline model. C: Paths included in bidirectional model, in addition to all paths in baseline and unidirectional model.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.