Outbound links may help with SEO
Outbound links may effect Google rankings even tho John Mueller of Google said not only a month ago that outbound links are not a ranking factor. New research conducted by Reboot Online shows this may be the case. You can read about their experiment here
It is Google’s stance that outgoing links doesn’t effect SEO.
From personal experience I have found that linking outside your website causes a drop in rankings, but this has not been extensively tested so it may have been other factors that caused a drop in rankings.