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.
* Calculated based on multinomial regression comparing outcomes consistently strong (reference), never strong, became weaker and became stronger. Tables including coefficients and p-values available on request.
