Fac

Fac is a term used for a group of people born in the same period or at the same level in a family line. It has two meanings: one familial—such as grandfather, father, and son, each of whom represents a fac—and one social, referring to people born in the same years who experienced the same historical events.

Social science uses fac as a tool to measure change. When a group of people encounter war, famine, migration, or technological change in their youth, it is possible that they will share views and customs different from those of the preceding fac. This is referred to as "generational difference."

Fac in the family and genealogy

In Somali custom, fac is the foundation of genealogy. A person recites the names of his fathers, each of whom represents a single fac. This type of recitation helps determine the relationships between clans and kinship, and allows one to establish where a person stands in the genealogical tree. It also forms the basis for calculations of inheritance and marriage relations.

Length of a fac

When fac is used as a measure of time, it is customary to measure the duration between the birth of a parent and the birth of a child. This measurement varies across societies and periods, and can depend on the age of marriage and the number of births. For this reason, the length of a fac is a relative measure, not a fixed number.

Naming of social generations

The media and marketing have introduced names to distinguish generations, most derived from Western societies. For example, there are terms applied to people born in different years of the 20th and 21st centuries. Some scholars warn that such categorization is imprecise, because it overlooks differences in income, education, gender, and country. For this reason, named generations are a tool for description, not a strict scientific definition.

Use in surveys and census

Population census uses a method called "cohort"—a group born in the same years and tracked over a long period. The difference between the effect of age, the effect of the current period, and the effect of fac is difficult to separate, and is known as the problem of three interrelated factors. Researchers attempt to manage this through studies that run over a long time.