Gallup finds that three-fourths of Americans favor raising the federal minimum wage to $9 an hour, whereas 22 percent oppose such a proposal. This is similar to what the Reason-Rupe poll found earlier this year; however, support flips and 56 percent oppose if it caused employers to lay off workers. All policies come with a price and polling questions constantly phrased as benefits-only propositions will continue to overestimate support. Instead, questions should measure what Americans would be willing to give up in order to raise the federal minimum wage.

This month New Jersey voters approved raising their state's minimum wage from $7.25 to $8.25 an hour by a margin of 61% to 39%. Two-thirds of the California state legislature also voted to increase the state's minimum wage to $10 an hour by 2016. In light of these numbers, Gallup's results suggest that national popular support is even higher.

However, simply asking if Americans favor or oppose a minimum wage increase suggest to survey respondents there are no costs associated with such a proposal. For those who haven't thought much about the issue, it's like asking if they want people to be paid more or less—not surprisingly they say more.

Instead, a Reason-Rupe poll delved deeper to understand how Americans make trade offs. First, it found a similar number to Gallup, that roughly 7 in 10 Americans support raising the minimum wage to $9 an hour assuming no costs. But a follow up question reveals that support plummets to 37 percent if doing so caused "some employers to lay off workers," and opposition raises to 56 percent.

The key is determining whether Americans actually believe raising the minimum wage will shrink the number of jobs in the economy. Reason-Rupe found 42 percent believe raising the minimum wage will reduce the number of jobs and 41 percent say it will have no impact. Thirteen percent actually thought it would increase the number of jobs.

Looking at the data's crosstabs, 58 percent of Americans who believe raising the minimum wage will lead to fewer jobs in the economy oppose the proposal. In contrast 88 percent of Americans who believe raising the minimum wage to $9 would have no impact on jobs favor raising the federal minimum wage. In other words, Americans who don't associate job costs with raising the minimum wage find little reason to oppose the proposal; those who expect a trade-off are less supportive.

These data suggest Americans' support for increasing the minimum wage is in large part contingent upon whether such a proposal would in fact actually impact jobs in the economy.

Moreover, rather than poll questions essentially asking respondents if they favor or oppose their fellow Americans making more money, questions should be designed to measure what Americans would be willing to give up to raise minimum wage floors.