• Data reference period
• Geographic localization (NUTS - 2013)
• Category of housing unit
• Tax residence of the purchaser
• Institutional sector of the purchaser

• TAX RESIDENCE:  Place of habitual residence for natural persons, place of the head office or effective management for legal persons or, failing that, the place of their permanent establishment in Portugal
• HOUSEHOLD DWELLING :  Dwelling that is normally intended to accommodate only one family, on the condition that it is not being used for other purposes at the period of reference.
• INSTITUTIONAL SECTOR:  Group of institutional units which have a similar type of economic behaviour.
• TRANSACTION:  Operation by which the ownership of a good is transferred through a counterparty.
• 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).

`VTRANSj = sum_(i=1)^n VTRANSij ` 

                      VTRANSij, Value of transactions of dwelling i in quarter j