Reference metadata describe statistical concepts and methodologies used for the collection and generation of data. They provide information on data quality and, since they are strongly content-oriented, assist users in interpreting the data. Reference metadata, unlike structural metadata, can be decoupled from the data.
The House Price Index (HPI) is a quarterly indicator that measures the changes in the dwellings' transaction prices that households acquire on the market. Prices include land value.
The data on the HPI is provided in the form of an overall index number comprising purchases for both newly built dwellings and existing dwellings.
The main variables in the dataset include: contract reference number, date of contract, deed type, sale price, square meterage (whenever available), property type and locality, amongst others.
The main sector covered by this dataset is S.14 as per ESA 2010 (Household sector). Size classes are based on the number of transactions recorded per quarter.
3.4. Statistical concepts and definitions
The HPI covers all transactions of dwellings made by households regardless of its final use. This index thus covers not only the transactions that are new to the household sector but also all that are traded between households. However, the data available precludes distinctions between: newly built and existing dwellings; and transactions between households and any other kind of transaction.
Index figures for the purchase of dwellings are compiled on the basis of full transaction prices, which are obtained from the Capital Transfer Duty within the Inland Revenue Department.
Prices of dwellings are gathered from notarial deeds of sales data provided by administrative source. Transaction prices refer to the price paid when the final deed is signed and ownership rights are transferred. Transaction prices include the value of land.
The HPI is a chain-linked Laspeyres-type price index. It is weighted by the value of dwelling transactions (new and existing) sector (gross concept applied, weights data include the value of land).
ESA 2010 is the main source for the compilation of weights, which is complemented by other construction statistics for the estimation of the weight for existing dwellings (e.g. building permits).
3.5. Statistical unit
Market prices of transactions in dwelling types that are most representative of the Maltese real estate market.
3.6. Statistical population
The target population is the set of all transactions of apartments, maisonettes and houses that are purchased by private households.
3.7. Reference area
Data are available for Malta and Gozo as a whole. Data by dwelling type (apartments, maisonettes and houses) or by district are available upon request.
3.8. Coverage - Time
Data reflecting dwelling transaction prices are available from the first quarter of 2005 onwards.
3.9. Base period
The HPI reference period is 2015 =100.
Index figures with reference year 2015 are available, as well as quarterly and annual growth rates in percentage form. Weights are given as parts in 1000. For now, the House Sales indicator is not being published. In the near future, further improvements are expected in the House Sales indicator.
The compiled quarterly indices represent the whole calendar quarter. The last four quarters are always provisional due to possible late contract registrations.
6.1. Institutional Mandate - legal acts and other agreements
The Malta Statistics Authority (MSA) Act empowers the NSO to collect, compile, extract and release official statistics related to demographic, social, environment, economic and general activities and conditions of Malta. National legislation is in line with the same EU requirements and methodology regarding the HPI.
Commission Implementing Regulation (EU) 2023/1470 of 17 July 2023 lays down the methodological and technical specifications in accordance with Regulation (EU) 2016/792 of the European Parliament and of the Council as regards the house price index and the owner-occupied housing price index, and amending Commission Regulation (EU) 2020/1148 (OJ L 181, 18.7.2023, p. 1–15).
No data sharing arrangements are in place. Internal data sharing is used for statistical purposes.
7.1. Confidentiality - policy
At National level:
The NSO requests information for the compilation of official statistics according to the articles of the MSA Act – Cap. 422 and the Data Protection Act – Cap. 586 of the Laws of Malta implementing the General Data Protection Regulations (GDPR).
Article 40 of the MSA Act stipulates the restrictions on the use of information while Article 41 stipulates the prohibition of disclosure of information. Furthermore, Section IX of the Act (Offences and Penalties) lays down the measures to be taken in case of unlawful exercise of any officer of statistics regarding the confidentiality of data.
Since its inception, the NSO has always assured that all data collected remains confidential and that it is used for statistical purposes only according to the articles and derogations stipulated in the laws quoted above. The Office is obliged to protect the identification of data providers and refrain from divulging any data to third parties that might lead to the identification of persons or entities.
During 2009, the NSO has set up a Statistical Disclosure Committee to ensure that statistical confidentiality is observed, especially when requests for microdata are received.
Upon employment, all NSO employees are informed of the rules and duties pertaining to confidential information and its treatment. In line with stipulations of the MSA Act, before commencing work, every employee is required to take an oath of secrecy whose text is included in the same Act.
An internal policy on anonymisation and pseudo-anonymisation is in place to ascertain that adequate methods are used for the protection of data which the office collects and shares with the public in its capacity as the National Statistics Office. The policy is meant to safeguard confidentiality of both personal and business data entrusted to the NSO. The document provides guidance for all NSO employees who process data on a daily basis as to how anonymisation and pseudo-anonymisation methods should be applied. The policy applies to all confidential, restricted and internal information, regardless of form (paper or electronic documents, applications and databases) that is received, processed, stored and disseminated by the NSO.
At European level:
Regulation (EC) No 223/2009 on European statistics (recital 24 and Article 20(4) of 11 March 2009 (OJ L 87, p. 164), stipulates the need to establish common principles and guidelines ensuring the confidentiality of data used for the production of European statistics and the access to those confidential data with due account for technical developments and the requirements of users in a democratic society.
7.2. Confidentiality - data treatment
Data are published in index format; hence confidentiality is preserved. Indices reflect price movements aggregated by different types of dwellings. This is in line with the Code of Practice - NSO Malta (gov.mt)
8.1. Release calendar
The release is published and disseminated at 11:00 hrs as scheduled in the advance Release Calendar. The calendar is published on the NSO website and includes a 3 month advance notice (the current month and the forthcoming two months).
All efforts are made so that the scheduled News Releases are published on the date and time announced. However, in the occurrence of unforeseen circumstances, News Releases may be deferred to a later time or to another date. In the latter instance, the NSO shall indicate clearly this deferral on the Advance Release Calendar with at least 3 working days notice. A note with the following text shall be included next to the postponed News Release 'postponed to dd/mm/yyyy'. The postponed News Release shall immediately be inserted in the new date within the Advance Release Calendar as indicated in the postponement notice.
An internal policy on dissemination is in place to govern the dissemination of official statistics in an impartial, independent and timely manner, making them available simultaneously to all users.
The NSO’s primary channel for the dissemination of official statistics is the NSO website. Tailored requests for statistical information may also be submitted through the NSO website.
National statistical releases are issued according to the release calendar and are made available to all users simultaneously. All releases are posted on the NSO website.
Dissemination to Eurostat for indices is on a quarterly basis and weights are disseminated annually. At national level the HPI is not published. Instead at a national level there are two news releases: a) the Property Price Index (PPI) which is published annually together with annual growth rates, and b) the Residential Property Transactions which is a monthly news release.
The NSO has developed an internal Quality Management Framework (QMF) which is built on common requirements of the ESS Code of Practice (ESS CoP). A document was prepared to include a set of general quality guidelines spanning over all statistical domains. Assuring methodological soundness is an integral part of the QMF, nonetheless, the document spans also on other areas related to institutional aspects.
11.1. Quality assurance
All data are checked for completeness and consistency with statistical concepts and definitions. The compilation of the PPI follows the methodology used in the OOH and the House Price Index (HPI) regulated by Eurostat. Also, reference to the respective manual is made during the computation of such indices.
The NSO has developed an internal Quality Management Framework (QMF) which is built on common requirements of the ESS Code of Practice (ESS CoP). A document was prepared to include a set of general quality guidelines spanning over all statistical domains. Assuring methodological soundness is an integral part of the QMF, nonetheless, the document spans also on other areas related to institutional aspects.
Every five to seven years, the NSO participates in a Peer Review exercise through which the compliance of its operations with principles of the ESS CoP is assessed by an expert team. Peer Reviews are indeed part of the European Statistical System (ESS) strategy to implement the ESS CoP.
11.2. Quality management - assessment
The quality of the HPI is routinely reviewed using a framework that is based on the OOH technical manual and the European Statistical System (ESS) definition of quality.
12.1. Relevance - User Needs
The HPI responds to the needs of all users interested in the developments taking place in the property market. These include private companies, students/academics, public corporations/government entities, international organisations and private users amongst others. Currently, the HPI does not provide information related to individual regions. Whenever possible, data requests can be custom-made according to the user's needs.
12.2. Relevance - User Satisfaction
The last User Satisfaction Survey was held in 2022 with the aim to collect information about key users’ satisfaction with statistical output. The NSO keeps record of the number of News Releases and publications disseminated on its website; the users to whom statistical products are provided; as well as the number of requests that are processed every year.
News Releases and tailor-made statistical outputs were assessed on account of their quality, timeliness, and on their ability to meet users’ needs.
12.3. Completeness
All relevant expenditure categories defined in Commission Implementing Regulation (EU) 2023/1470. For the compilation of data, consistency is ensured by following both guidelines and regulations. Furthermore, data completeness is ensured for any requests received by third parties.
13.1. Accuracy - overall
The HPI gives a good indication of what’s going on in the property market in relation to property prices.
13.2. Sampling error
All Residential Property Price Indices (RPPI) are based on administrative sources that cover the entire population of transacted properties.
13.3. Non-sampling error
Index numbers are based on data obtained from an administrative source. It can be the case that there are inconsistencies (due to misclassification) in this data. The Prices Unit is putting its efforts in minimizing these errors.
14.1. Timeliness
Data are sent quarterly according to the Residential Property Price Indices (RPPI) data transmission guidelines. There is no time lag (in days) between the end of the period to which the HPI relates to the PPI. The only difference is in the frequency of publication, and consequently, the HPI is more relevant than the PPI. The PPI is published once every year, whilst the HPI is published every quarter. The HPI is not published on a national level. Since the PPI is an annual news release, we publish the first quarter of the reference year, and, the second, the third and the forth quarter of the previous year. The national publication is on the same day as the HPI, or a day before or after. The PPI is usually published around t+90 days from the reference period.
14.2. Punctuality
Deadlines have always been met and data is sent typically according to Commission Implementing Regulation (EU) 2023/1470, T+85 days. Time lag occurs only in the case where data queries are sent to the data provider. For such situations, the Price Statistics Unit is currently doing an exercise with Inland Revenue Department (IRD) to reduce these queries.
15.1. Comparability - geographical
Data are comparable across NUTS II regions.
15.2. Comparability - over time
The HPI was revised from 2023 Q1 onwards, whilst making use of the Splicing Technique to compensate for the break in series when linking with the old index. This allows the continuity of the HPI by joining the two time series at one specific time period.
15.3. Coherence - cross domain
The PPI and the House Price Index (HPI), both measure changes in property prices. To ensure coherency between the two indices, the same methodology is used.
Consistency is also ensured between the HPI and OOHPI sub-indices for the acquisition of dwellings.
15.4. Coherence - internal
The overall indices and their subdivisions are consistently calculated. To ensure internal consistency, the HPI and the OOHPI sub-indices for the acquisition of dwellings, are compared.
As data is obtained from an administrative source, there are no costs involved. In order to reduce the burden, data is provided by the source at the beginning of every month via email. Data consists of a register and as stipulated by the law, contract transactions must be registered with the tax department. Other costs involve the salary of the employee/s working on the compilation of such indices.
17.1. Data revision - policy
The standards specified in Commission Implementing Regulation (EU) 2023/1470 are applied. HPI data are revisable. The data for the last four quarters are always flagged as provisional due to late contract registrations by the notaries.
17.2. Data revision - practice
The general public is informed about possible non-periodic revisions in the press releases. Data for the last four quarters is flagged as provisional due to late contract registrations by notaries.
18.1. Source data
See below.
18.1.1. Prices
Index numbers are compiled on administrative source data, obtained from the Capital Transfer Duty within the Inland Revenue Department.
18.1.2. Weights
HPI weights are based on actual dwelling transaction values. The partition of the total HPI weight into new and existing dwellings is done using information available from the same source as used for prices.
18.1.3. Source data - House Sales indicators
House Sales are based on actual dwelling transaction values and counts. The partition of the total House Sales is done using information available from the same source as used for prices and weights.
18.2. Frequency of data collection
All data are provided by the data source on a monthly basis.
18.3. Data collection
Administrative data are obtained via email.
18.4. Data validation
Various procedures ensure that errors are minimised in the data. The following validation checks are made on each record in the source data:
extreme values are identified and eliminated if thought necessary;
data cleaning is done to remove cases of obviously erroneous data;
minimum and maximum values are investigated and removed if believed to be suspect;
number of signed transactions is compared with previous months and/or quarters;
data gaps are minimised by merging the three separate datasets into a single one.
The aggregate output is compared with those from previous quarters.
18.5. Data compilation
See below.
18.5.1. Calculation and Aggregation
See below.
18.5.1.1. Index formulae
HPI is a Laspeyres-type price index.
18.5.1.2. Aggregation method
First, a separate index for each dwelling type is compiled. Then, the weights are used to compile the HPI sub-indices and the overall HPI. Weights are representative of the year t-1, and based on data on household expenditure on transacted dwellings that belong to the target population of the HPI. The HPI is a Laspeyres-type index that is chained on a yearly basis using the fourth quarter of the previous year as the linking period. The index is produced with 2015 = 100.
18.5.1.3. Derivation of sub-index and elementary aggregate weights
The sub-index and elementary aggregate weights are based on data on household expenditure on transacted dwellings. The weights used to compile the index are based on the value of transactions for the three property types (apartments, maisonettes and houses).Weights are based on the data from year t-1, and revised on an annual basis.
18.5.1.4. Price updating
Elementary aggregate weights are adjusted with an appropriate price change between the year t-1 and the fourth quarter of the year t-1.
18.5.1.5. Chaining and linking method
The HPI is chain-linked every year, using the fourth quarter of the previous year as the linking period. This enables the revision of weights on an annual basis, thus ensuring that the index is relevant at all times.
18.5.1.6. Compilation of sub-indices
The HPI is based on the Hedonic method for each dwelling type.
18.5.1.6.1. Hedonic method
The index compilation method is the Rolling Time Dummy method where the result for each reference period is based on a rolling window of quarters. The optimal window length was analysed for each property type. The log price is the dependent variable. The independent variables include: log of the square metreage, dwelling subtypes, and geographical location, amongst others. First, the hedonic models for the three main property types distinguished within each of the two sub-indices (newly built and existing dwellings) are compiled, and then indices for property types are aggregated with the use of weights in order to obtain indices for newly built dwellings, existing dwelling and total HPI.
18.5.1.6.2. SPAR method
Not applicable.
18.5.1.6.3. Stratification
The main strata consist of the three main dwelling types: apartments, maisonettes and houses.
18.5.2. Other processing issues
See below.
18.5.2.1. Timing for pricing
The price of the dwelling is the price in the final sale contract, i.e. after transfer of ownership rights. The date of the final deed is used to allocate the transactions with the respective month/quarter.
18.5.2.2. Treatment of VAT
VAT is not included in the price of new dwellings.
18.5.2.3. Treatment of other taxes
Taxes other than VAT are not included in the price of dwellings.
18.5.2.4. Treatment of government subsidies
The HPI includes only transactions at market prices.
18.5.2.5. Treatment of land
The price of land is included in both prices and weights.
18.5.2.6. Housing cooperatives
Housing cooperatives are not covered in the HPI.
18.5.2.7. Treatment of non-market transactions
Non-market transactions are identified from the price variable. This is usually very low, or not available. Information from other variables may be used, as well.
18.5.2.8. Treatment of multi-object transactions
Price and square metre information is disaggregated when multiple dwellings are transacted in one contract.
18.5.2.9. Treatment of fractional transactions
These are identified and excluded from the HPI, as the selling price is usually below market value.
18.5.2.10. Outliers detection
Outliers are detected using Cook’s Distance. The data is checked for persisting highly influential transactions that remain after the outlier detection. These are identified and eliminated if thought necessary.
18.5.2.11. Treatment of incomplete data source coverage
Not applicable.
18.6. Adjustment
Elementary indices are smoothed by attributing weights for the last quarters where the most recent ones have the bigger share.
No further comments.
The House Price Index (HPI) is a quarterly indicator that measures the changes in the dwellings' transaction prices that households acquire on the market. Prices include land value.
The data on the HPI is provided in the form of an overall index number comprising purchases for both newly built dwellings and existing dwellings.
The main variables in the dataset include: contract reference number, date of contract, deed type, sale price, square meterage (whenever available), property type and locality, amongst others.
The HPI covers all transactions of dwellings made by households regardless of its final use. This index thus covers not only the transactions that are new to the household sector but also all that are traded between households. However, the data available precludes distinctions between: newly built and existing dwellings; and transactions between households and any other kind of transaction.
Index figures for the purchase of dwellings are compiled on the basis of full transaction prices, which are obtained from the Capital Transfer Duty within the Inland Revenue Department.
Prices of dwellings are gathered from notarial deeds of sales data provided by administrative source. Transaction prices refer to the price paid when the final deed is signed and ownership rights are transferred. Transaction prices include the value of land.
The HPI is a chain-linked Laspeyres-type price index. It is weighted by the value of dwelling transactions (new and existing) sector (gross concept applied, weights data include the value of land).
ESA 2010 is the main source for the compilation of weights, which is complemented by other construction statistics for the estimation of the weight for existing dwellings (e.g. building permits).
Market prices of transactions in dwelling types that are most representative of the Maltese real estate market.
The target population is the set of all transactions of apartments, maisonettes and houses that are purchased by private households.
Data are available for Malta and Gozo as a whole. Data by dwelling type (apartments, maisonettes and houses) or by district are available upon request.
The compiled quarterly indices represent the whole calendar quarter. The last four quarters are always provisional due to possible late contract registrations.
The HPI gives a good indication of what’s going on in the property market in relation to property prices.
Index figures with reference year 2015 are available, as well as quarterly and annual growth rates in percentage form. Weights are given as parts in 1000. For now, the House Sales indicator is not being published. In the near future, further improvements are expected in the House Sales indicator.
See below.
See below.
Dissemination to Eurostat for indices is on a quarterly basis and weights are disseminated annually. At national level the HPI is not published. Instead at a national level there are two news releases: a) the Property Price Index (PPI) which is published annually together with annual growth rates, and b) the Residential Property Transactions which is a monthly news release.
Data are sent quarterly according to the Residential Property Price Indices (RPPI) data transmission guidelines. There is no time lag (in days) between the end of the period to which the HPI relates to the PPI. The only difference is in the frequency of publication, and consequently, the HPI is more relevant than the PPI. The PPI is published once every year, whilst the HPI is published every quarter. The HPI is not published on a national level. Since the PPI is an annual news release, we publish the first quarter of the reference year, and, the second, the third and the forth quarter of the previous year. The national publication is on the same day as the HPI, or a day before or after. The PPI is usually published around t+90 days from the reference period.
Data are comparable across NUTS II regions.
The HPI was revised from 2023 Q1 onwards, whilst making use of the Splicing Technique to compensate for the break in series when linking with the old index. This allows the continuity of the HPI by joining the two time series at one specific time period.
