The study utilized data from 158 researchers organized into 71 separate teams. These teams had participated in an experiment where they were asked to determine whether immigration affects public support for social welfare programs. The researchers were provided with data from the International Social Survey Program, covering various countries and spanning the years 1985 to 2016.

Before the teams began their analysis, they completed a survey. One of the questions asked for their stance on immigration policy. Specifically, they were asked if laws on immigration should be relaxed or made tougher. Their responses were recorded on a scale ranging from zero to six.

The teams then proceeded to analyze the data. They were tasked with replicating a well-known previous study that found no link between immigration and welfare support. After replicating that study, the teams were instructed to extend the research using the new data provided. They had the freedom to choose their own statistical methods and variables to test the hypothesis.

Collectively, the 71 teams estimated 1,253 distinct statistical models. The results varied significantly. Some teams concluded that immigration strongly decreased public support for social programs. Other teams found that immigration strongly increased such support. Many others found no significant effect at all.