Joshua Project offers two ways of viewing the same people group data:
This method counts a people group for each country it lives in and is called People Group In Country (PGIC). For example, the Bambara in Mali are considered a distinct people group. If the Bambara live in 12 countries they are counted as 12 people groups. Of the 16,402 people groups in country, 7,140 are considered unreached and 4,794 are frontier unreached.

This method counts a people group once regardless of how many countries they live in and is called People Group Across Countries (PGAC). For example, if the Bambara live in 12 countries they are counted as only one people group. Of the 10,422 people groups across countries, 4,488 are unreached and 3,215 are frontier unreached.
