What “treatments” change behavior? Â Will higher taxes lead golf’s Phil Mickelson to play fewer rounds? Â He said so but since we will never observe his 2013 golf schedule had the Bush Tax Cuts lived on, we don’t know. Â Â In the case of energy efficiency, which investments are cost-effective? Â In this Opinion Piece, Catherine Wolfram makes the case for implementing more field experiments so that there is a kosher treatment group whose behavior can be compared to a control group. Â Macro policy makers can’t run credible field experiments since there is no contemporaneous control group. Â If Â Congress could randomly raise taxes for half of the population, the CBO could measure whether this treatment group works less. In this case, Â we would learn something about how the rest of the population would be affected by increasing taxes on them. Â When you can’t randomize incentives, how do we establish cause and effect? Â Many economists continue to grapple with this tough issue.