tax proponents response to empirical evidence on volatility Lack of direct supporting evidence for stabilizing (volatility-reducing) properties of Tobin-style transaction taxes in econometric research is acknowledged by some of the Tobin tax supporters: These Tobin tax proponents propose on indirect evidence in their favor, reinterpreting studies which do not deal directly with volatility, but instead with trading volume (with volume being generally reduced by transaction taxes, though it constitutes their tax base, see: negative feedback loop). This allows these Tobin tax proponents to state that "some studies show (implicitly) that higher transaction costs might dampen price volatility. This is so because these studies report that a reduction of trading activities is associated with lower price volatility." So if a study finds that reducing trading volume or trading frequency reduces volatility, these Tobin tax supporters combine it with the observation that Tobin-style taxes are volume-reducing, and thus should also indirectly reduce volatility ("this finding implies a negative relationship between [..] transaction tax [..] and volatility, because higher transaction costs will 'ceteris paribus' always dampen trading activities)." (Schulmeister et al., 2008, p. 18). Some Tobin tax supporters argue that volatility is better defined as a "long-term overshooting of speculative prices" than by standard statistical definitions (e.g., conditional variance of returns) ) which are typically used in empirical studies of volatility. The lack of empirical evidence to support or clearly refute the Tobin tax proponents' claim it will reduce "excess" volatility is due in part to a lack of an agreed definition of "excess" volatility that allows to be distinguished and formally measured. Should speculators be encouraged, penalized or dissuaded? The Tobin tax rests on the premise that speculators ought to be, as Tobin puts it, "dissuaded." This premise itself is a matter of debate: See Speculation. On the other side of the debate were the leaders of Germany who, in May 2008, planned to propose a worldwide ban on oil trading by speculators, blaming the 2008 oil price rises on manipulation by hedge funds. At that time India, with similar concerns, had already suspended futures trading of five commodities. On December 3, 2009, US Congressman Peter DeFazio stated, "The American taxpayers bailed out Wall Street during a crisis brought on by reckless speculation in the financial markets, ... This [ proposed financial transaction tax ] legislation will force Wall Street to do their part and put people displaced by that crisis back