- Correspondence to Dr William G Shadel, RAND Corporation 4570 Fifth Avenue, Suite 600, Pittsburgh, PA 15213-2665, USA;
- Received June 12, 2015
- Revised October 12, 2015
- Accepted October 28, 2015
- First published November 23, 2015.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.