How the data was compiled
THE Independent.ie Data Science team analysed more than 192,000 transactions recorded on the Property Price register (www.propertypriceregister.ie) between January 1, 2010, and March 16, 2016.
The aim was to find information on transactions involving the sale of multiple units at the same address on the same date, also known as block sales. This would indicate sales where investors had bought a number of units.
While the register contains information from stamp duty returns made to the Revenue Commissioners, and includes the date of sale, amount paid, address of the property and whether it is new or second-hand, it is difficult to use.
This is because in some cases, each unit sold in a development is recorded as an individual transaction. In other cases, an entire block is listed as one sale.
As the address information for properties is unstructured, the data science team had to perform a data cleansing task, which included removing the house or apartment numbers, removing additional information such as car parking spaces, expanding commonly used abbreviations such as Rd, Dr or Cl and replacing them with Road, Drive or Close.
After the addresses were cleaned up, all matching addresses sold on the same date were grouped together into bulk sales. The data was rechecked against the property price register.
The numbers purchased in individual transactions ranged from two to hundreds. In some cases, sales of multiple units were recorded across a number of transactions.
A decision was made to focus on sales where 10 or more units were sold. This would weed out smaller investors.
Many of the units were in unfinished developments, meaning that they would need substantial funding in order to complete them before they could be rented or sold. Among the buyers are large investment funds as well as Real Estate Investment Trusts (REITs).