Recently, the Pew Research Center released its sixth annual report examining global restrictions on religion. The report is a huge undertaking, detailing both government restrictions on religion and social hostilities toward religious groups in nearly 200 countries and territories.

Fact Tank sat down with Peter Henne, the study’s lead researcher, to learn more about the complex process of measuring religious restrictions.

Why do you measure global restrictions on religion rather than “religious freedom”?

We look for evidence of restrictions on religious belief and practice because they can be easier to measure in a transparent and objective manner. For example, we can find information on government policies that restrict certain types of religious practice – like conversion – but it is less likely that there will be information indicating whether individuals in a particular country feel free to convert from one religion to another.

Very broadly, we look at two types of activities in each country. First, we examine a variety of government policies or initiatives that restrict religious belief or practice. And then, in order to capture all aspects of restrictions on religion, we also look at actions by private individuals and groups in society – something we call “social hostilities” – that affect religious expression and practice. These social hostilities involving religion can be just as significant as government actions.

In looking at these two areas – government restrictions and social hostilities – we use a methodology developed by Brian J. Grim, formerly of the Pew Research Center, and Roger Finke, a professor of sociology and religious studies at Pennsylvania State University. We identify 20 types of government restrictions on religion, which range from official favoritism toward a religious group to legal restrictions on an individual’s ability to convert to another religion to officially sanctioned violence and abuse against religious groups. We also identify 13 types of social hostilities involving religion, from mob violence relating to religion to religion-related terrorism to harassment of women over religious dress. We then rate each country in these two categories with a number from zero to 10, the latter indicating the country had every type of restriction or hostility in place. So each country has two numbers, one representing government restriction of religion and the other measuring social hostility involving religion.

How do you collect the information that you use and why is it over a year old?

We draw on numerous reports by the U.S. government, the United Nations, the European Union and nongovernmental organizations involved with religious freedom and human rights. Our primary source is the U.S. State Department’s International Religious Freedom report, which catalogs the status of religious freedom in every country around the world. Other sources, including country reports by Amnesty International and the U.N. Special Rapporteur for Religious Freedom and Belief, provide additional information and a broader perspective on these issues. A team of data coders then goes through the sources and records which types of government restrictions and social hostilities were present in the countries and how severe they were. We then turn these answers into numbers. Because we rely on these government and NGO reports – instead of using newspaper articles – there is a delay between when an event occurs and when we release our report. Most of the source reports come out a few months after the year they cover because it takes time to collect and analyze the information; our coding and analysis also takes time. There are benefits to this approach, however. By relying on numerous well-regarded reports we know we are basing our study on consistent and reliable information.

How do you ensure that the information is accurate?

We have numerous quality-control procedures during both the data coding and afterwards. For example, the coders follow a double-blind procedure, in which two coders work on the same country, sorting through the material independently of the other. After finishing, they compare their evaluations to determine the final assessment. This provides a double check of all coding and prevents any coders from affecting others’ answers by discussing them before they are done. We also conduct some tests after the data is collected. For example, we wrote a case study – separate from our annual report – on the different types of government restrictions and social hostilities occurring in Mexico, based on Spanish-language newspaper articles from Mexico. We then compared what we found in the newspaper articles to our government and social hostility scores for Mexico. The two lined up well, indicating that the sources we used for the reports accurately portrayed the countries they covered.

Are there differences in the ways you measure religious restrictions and hostilities in the U.S.?

The data collection process for the U.S. is slightly different than for the rest of the world since our primary source for the entire report, the U.S. State Department’s International Religious Freedom Report, does not cover the U.S. To make sure we are not missing important issues in the U.S., we also look at sources from the U.S. Department of Justice and FBI on religious freedom and hate crime incidents. By using these sources, we help make sure the United States’ scores are comparable to the rest of the world’s.

David Masci  is a former senior writer/editor focusing on religion at Pew Research Center.