Immigration policy and reform debates test our ability to think about what’s at stake when we open (and close) our doors to a diverse range of newcomers, and how ongoing immigration affects our future. As the debate on how immigrant workers and families continue to reshape the country gathers steam, the public is often misled about the challenges and opportunities stemming from policies about who can come to (and stay in) the US.

Typically, two questions come up most often: How much of an economic and fiscal impact do immigrants have at the federal, state and local level? What are the range of impacts, including costs and benefits?

Casual consumers of information will come across a flurry of mixed messages from abundant studies of varying quality.

Reliable studies lay out researchers’ decisions, such as:

  • Research questions and design: what pieces of a policy puzzle to examine and how to carry out a study;
  • Data sources: where to look for information (or how to arrive at estimates) to help answer our questions;
  • Data collection: how to keep track of the important parts of the puzzle we want to figure out; and
  • Research methods: what kind of analysis can best help us answer our questions.

These decisions should be honest and transparent, and limitations—especially those related to findings—should be presented up front. All researchers make these decisions, though not all studies are equally defensible.

In cases where rigorous research doesn’t yield the expected results, some analysts are tempted to pick and choose only the evidence that supports their opinion and to ignore or downplay the rest. Such exercises amount to putting your thumb on the scale to make sure the results come out the way you want them. Below are a few signs that a study is not reliable and best passed over in favor of findings based on more solid research questions and methods.

To avoid being misled, consider the source and whether a study is promoting an agenda. To determine whether a study should be taken seriously, look closely at both sides of the cost-benefit ledger: do you get the impression that authors brainstormed every conceivable cost and then defined benefits to include the narrowest possible types of contributions, or vice versa? If so, such an analysis does not advance our national dialogue.

Some observers start with a research question that barely conceals a predetermined position. For example, an unbiased report does not start by asking: how much do immigrants drain welfare and schools? Likewise, a complete study should acknowledge that each level of government devotes resources to incorporate newcomers. Moreover, if a report claims to tell you the number of dollars that “illegal aliens” cost the taxpayer, be skeptical. Since there is no definitive source of data for the number of unauthorized immigrants and their involvement with various public programs or their exact contributions, all studies rely on estimates and all estimates have limitations. Be especially skeptical if these estimates make no distinction between “non-citizens,” legal permanent residents, unauthorized immigrants (those who overstay visas or enter the U.S. without invitation), and naturalized citizens. Finally, a serious person does not conflate “unauthorized immigrant” with “U.S. born children of unauthorized immigrants.” Few things tilt the scales more effectively than forgetting that someone born in this country is not an immigrant.

For examples of a comprehensive approach to studying the costs and benefits of immigration, consider a 2007 study published by The Urban Institute on the net economic and fiscal effects of immigrants on Arkansas. More recently, a 2008 Nebraska study examined the economic and fiscal impacts of the state’s immigrant population. Both studies present a comprehensive snapshot of the effects that a population can have on a state’s economy. The authors applied a tested research method (e.g., an input-output model) that can reasonably capture the full set of important economic and fiscal costs and benefits. They also spell out the decisions they made—including simulations based on population estimates—when analyzing their information and acknowledge their research limitations.

As the immigration reform debate continues, we should be prepared to interrogate analyses and distinguish between rigorous research and opinionated information disguised as research. Otherwise, the policies we choose about who can come to (and stay in) the U.S. will be based on little more than anecdotes and bias.

*Juan M. Pedroza and Molly Scott are Research Associates and Rob Santos a Senior Methodologist at The Urban Institute. The Urban Institute is a nonprofit, nonpartisan policy research and educational organization that examines the social, economic, and governance problems facing the nation. The views expressed above are those of the author and should not be attributed to the Urban Institute, its trustees, or its funders.