"The urban legend (that Facebook is losing younger users) flows more often than not from surveys people have done of younger users that indicate that they're using other social services ... much of the concern stems from the assumption that this is a zero-sum game, and that's not how we see it, " Ebersman said.

CNN: Survey: Teens' enthusiasm for Facebook is waning

Much of Mr Obama's policy rests on the assumption that Russia still wants to sit at the same table as America and be integrated into world structures.

ECONOMIST: Russian-American relations

And much of the attention has focused on video, on the assumption that, surely, that is what people want to share.

FORBES: Lightt App Compresses Time, Collapses Space and Creates A New Kind Of Social Stream

The assumption built into mainstream economics is much closer to the second of these than the first.

ECONOMIST: The benevolence of self-interest | The

Those moves by borrowers are hurting investors who bought bonds on the assumption that the pace of refinancing and repayments would be much slower.

WSJ: When Good News for Real Estate Is Bad

From kindergarten on we were taught what can be described as prediction reasoning, a way of thinking based on the assumption that the future is going to be pretty much like the past.

FORBES: How To Create What You Want In An Uncertain World

When risk managers can do assumption testing on those models, they are much better able to see the validity of the models used across the organization and get a more informed debate rather than listening to trader, who say that because they are making loads of money their models must be right.

FORBES: SAS Moves Enterprise Risk to Near Real-Time

CBO's report was careful to explain that under the assumption that some of these policies will be extended, its forecast would have looked much more similar to other forecasts.

WHITEHOUSE: Detailing the FY2011 Budget