Above all else, the study underscores that while meat production will need to change in the future, so will meat consumption. It’s difficult to get a full and proper accounting of the total environmental impact of livestock production. A 2006 report from the Food and Agriculture Organization estimated that livestock were responsible for about 18% of human-caused greenhouse gases — a figure that has been criticized by the meat industry as too high and by some environmentalists as far too low . But what’s clear is that American levels of meat consumption can’t be sustainably adopted by the rest of the world, even if livestock management becomes more efficient globally. “Demand management has to be part of the solution as well,” says Herrero. For the environment — and for our hearts and waistlines too.
Journals may also attempt to limit the number of "citable items"—., the denominator of the impact factor equation—either by declining to publish articles that are unlikely to be cited (such as case reports in medical journals) or by altering articles (., by not allowing an abstract or bibliography in hopes that Journal Citation Reports will not deem it a "citable item"). As a result of negotiations over whether items are "citable", impact factor variations of more than 300% have been observed.  Items considered to be uncitable—and thus are not incorporated in impact factor calculations—can, if cited, still enter into the numerator part of the equation despite the ease with which such citations could be excluded. This effect is hard to evaluate, for the distinction between editorial comment and short original articles is not always obvious. For example, letters to the editor may refer to either class.
In estimating the impacts on economic activity and employment from undoing these spending caps, we assume that the composition of discretionary spending is essentially unchanged by shifts in the level of spending. It is theoretically true that cuts to infrastructure spending could be less or more steep than overall spending cuts, but this is nearly impossible to forecast. Further, the discretionary spending cuts currently constituting the policy baseline in the United States (., the budget “sequester”) are across-the-board cuts to every category of discretionary spending, making the assumption that the composition of discretionary spending cuts will be unaffected by the level in fact consistent with current budget law.