Glassdoor compiled a bunch of quotes from employees at these firms, explaining why they believe their companies are so optimistic. (Glassdoor allows current and former employees to share their experiences and rate companies they've worked at.)
The information is based on companies with at least 20 business outlook ratings and at least 20 company reviews during April 2013. Company ratings are based on a 5-point scale: 1.0=very dissatisfied, 3.0=OK, 5.0=very satisfied.