Making demographic comparisons across datasets and across time requires rigor and consistency in group definitions. Without this, one risks reporting change that is not real. Since some of our definitions may differ from those used by the Census Bureau or other data providers, we make a point of specificity and transparency on this front.

Some of the key definitions that we rely on at Pew Research Center include:

Race and ethnicity: The terms “whites,” “blacks” and “Asians” generally are used to refer to the non-Hispanic components of each population. Any respondent who reports Hispanic origin is defined as Hispanic.

Generations: Some of Pew Research’s demographic analysis has focused on generations, which are a somewhat imprecise but useful cultural grouping of Americans by age. The definitions we use in our work are:

Millennial adults Gen Xers Baby Boomers Silents Greatest
Born… After 1980 1965-1980 1946-1964 1928-1945 1927 and earlier
Age in 2014… 18-33 34-49 50-68 69-86 87 and older

Married: For most of our work, we calculate marital status based on adults ages 18 and older (the Census Bureau uses 15 and older). When looking at births or motherhood, however, we often use ages 15 and older.

Puerto Ricans: In domestic political research, we generally include Puerto Ricans with the U.S.-born population. However, if the report is about language, assimilation or an international topic, we use the U.N. definition and treat Puerto Ricans as foreign born because their experiences more likely resemble those of immigrants from Latin America.

Immigrant generation: In Pew Research Center work, “first-generation” immigrants refer to the person who came to live in the United States from another country, not that person’s native-born offspring. “Second generation” refers to a U.S. native with at least one first-generation parent. And “third generation” refers to a U.S. native whose parents are also U.S. natives.