In a word, the fiscal cliff negotiations are about avoiding the CBO baseline scenario .

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According to their baseline scenario, U.S. GDP is expected to grow just 2.2% this year and 1.8% in 2013.

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Under the baseline scenario net interest payments would hit about three percent of GDP in the 2020s and then drop.

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Under the extended-baseline scenario, U.S. public debt relative to GDP, which was 37% at the end of fiscal 2007, drops to 25% of GDP by the end of fiscal 2025.

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To make the debate on NHS reform comprehensible, and the claims testable against evidence, what we need is some form of baseline scenario that explains the level of productivity improvement needed to keep health costs below double their present cost.

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Taking those effects into account, CBO estimates that under the extended-baseline scenario, real (inflation-adjusted) gross national product (GNP) would be reduced slightly by 2025 and by as much as 2 percent by 2035, compared with what it would be under the stable economic environment that underlies most of the projections in this report.

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Probabilities are applied to that scenario and a baseline established.

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