Introduction
In Statistics Finland, we gather data on advertisements of houses for sale and rent based on a contract with one of the largest providers in the market, which is a self-service for selling and renting real property online. This marketplace, Oikotie.fi, contains a vast coverage of advertisements in Finland. Many kinds of agents use this service, for example, private persons, companies, and municipalities to sell and rent out. In addition, one can market their property via real estate agents.
The data we receive shows approximately 40,000 to 60,000 houses and apartments for sale and 20,000 to 40,000 for monthly rent. The service includes summer cottages and other vacation residences, garages, plots, and forest land. However, for Statistics Finland, we only gather data on houses and apartments, with vacation homes excluded.
The data are used for project purposes and to produce experimental statistics that are published quarterly. Cooperation with Oikotie was first established in 2020. At the time of writing, the data spans from 2019 to the end of 2024.
Contacting and choosing data providers
In the Finnish rental market, the key players regarding rental advertisements are Etuovi and Vuokraovi, owned by Alma Media, and Oikotie. Private landlords mainly advertise through these services. In negotiations with these operators, mutual data collaboration was also discussed.
However, we found that the proportion of rental advertisement data from private individuals on Vuokraovi was insufficient. Oikotie's dataset covers private individuals' rental advertisement information more comprehensively. Oikotie's dataset needed to be available without publication accuracy restrictions. Restrictions imposed on the Vuokraovi dataset would have poorly suited the requirements for statistical production.
Main agreement conditions
In Statistics Finland, there is a specific team that deals with agreements, contracts, and the legal aspect of data gathering. The contract is revised and signed yearly to agree on price and other agreement conditions, such as data transfer, contents, and usage. There is a noted contact person from both sides of the agreement.
Statistics Finland (SF) is committed not to use the data for commercial purposes. All rights are reserved, so SF may not transfer data forward to third parties or publish the data without permission. The data may not be used to identify persons.
The CSV data files for sales and rents are gathered once a month via an automatic interface search. In case of data problems, we can contact a specific help email for fast problem-solving. Possible changes made by the provider that might affect the interface search we do will be reported to us beforehand unless the change is related to privacy protection. We should be informed of the biggest changes at least 30 days before.
For example, due to some discussions a few years ago, we added more new variables to the data for all future deliveries. We were informed about the schedule and received updated variable descriptions. Updating or adding contract attachments requires written approval from both parties. SF is responsible for making these updates.
Data set variables
Oikotie data comprises about 70 variables in each sale and rent data set. They describe all the fields of a form that are fillable by online users advertising on the website. Some are mandatory, and many are optional. Nearly all the variables are common to both sales and rent data sets.
Advertisements are identified by a unique ID generated by Oikotie. We can also distinguish the type of advertiser, whether a private person or a company.
Most variables describe the properties of the apartments and buildings. These include whether there is a balcony, lift, or sauna, how many floors and rooms there are, the year of the house's construction, the building type, and the condition.
Locational variables are country, street, postal code, coordinates, city, and district. Some apartments and houses are located outside Finland but omitted for statistical purposes.
Prices are unencumbered listing prices, and rents are monthly rents. For short-term renting, there are extra variables such as rent per week, weekend, and day and whether an apartment is rented furnished or not. With these, we can narrow down the scope of experimental statistics to long-term renting only.
Advertisement publication and expiration dates are used to identify the number of added and removed advertisements each month for the experimental statistics. We also publish averages and means of the number of days and how long advertisements have been active online.
Potential and future plans
The experimental statistics on housing advertisements have been a success. They add a new dimension of supply and demand indicators on house markets alongside the official statistics. They are among the top-viewed experimental statistics and have received good feedback from users.
We have used the data for a couple of projects: to link asking prices in Oikotie to realized prices gathered from the tax administration. This aims to produce a locational and temporal comparison between these two and to get more profound information on economic cycles in the housing market.
Eurostat-funded project is underway to enhance the quality of rental data for the Harmonised Index of Consumer Prices (HICP) using rental advertisement data. The project investigates whether the requested rent information from rental advertisements can complement other statistical data, including monthly rents. Oikotie's rental advertisement data will potentially become part of regular rent statistics production in the coming years.