Can anyone clarify in "layman's" terms how the HUD Median Family Income is arrived at? What is meant by "family" 1 or more persons?

If you search the HUD web site you will find the definition and information on a complicated mathematical formula used to project income.

The census is taken every 10 years but between census demographics change. HUD is making a projection of income in order to keep data somewhat current.

Families and Households are two classifications used in a census. One person in every household is designated as a householder. A family is a group of individuals related to the householder. All non related individuals and related individuals are the number in a household. If no one in the household is related they are counted as a Nonfamily household