• Data reference period
• Place of residence (NUTS - 2013)
• Sex

• RESIDENT POPULATION:  Set of persons who, regardless of being present or absent in a given housing unit at the moment of observation, have lived in the place of their usual residence for a continuous period of 12 months prior to the moment of observation, or have arrived to the place of their usual residence during the period of 12 months prior to the moment of observation, with the purpose of living there for a year, at least.
• REFERENCE PERIOD:  Period to which the information refers and which may be a specific day or a time interval (month, fiscal year, calendar year, among others).
• MEDIAN AGE OF RESIDENT POPULATION:  Age that divides a population into two numerically equal groups, i.e., half of the people are younger than this age and half are older.

The median is that value of the variate which divides the total frequency into two halves. 50% of the scores are above and 50% are below that vale.