3. Background information: sources, methods, definitions and uses of the data
3.1 Household estimates from Council Tax systems
In order to administer Council Tax, each local authority keeps a record of all dwellings, as well as information on certain categories such as vacant dwellings and second homes. National Records of Scotland (NRS) collects a summary of this information, and uses it to estimate the number of dwellings that are occupied or vacant, by subtracting the number of dwellings which are vacant or second homes from the total number of dwellings. An occupied dwelling is approximately equivalent to a household.
Some additional information is also included. Firstly, the number of dwellings which receive a 'single adult' discount because they contain just one adult, living alone or with children or adults who are 'disregarded' for Council Tax purposes. Secondly, certain types of dwellings are occupied but exempt from paying Council Tax, such as all-student households and dwellings which are owned by the Secretary of State for Defence for providing armed forces accommodation.
Definitions of household characteristics from Council Tax billing systems
| Category | Description |
| All dwellings | This is the total number of dwellings on the Council Tax valuation list (excluding free-standing private lock-ups and garages). A 'dwelling' refers to the accommodation itself, for example a house or a flat and includes second homes that are not let out commercially. Caravans count as dwellings if they are someone's main home. |
| Vacant dwellings |
This includes:
|
| Second homes | Dwellings subject to a Council Tax discount of between 10 per cent and 50 per cent due to being second homes. This includes self-catering holiday accommodation available to let for a total of less than 140 days per year. |
| Occupied dwellings | All dwellings, minus those which are vacant or second homes. |
| Single adult discounts |
Dwellings subject to a Council Tax discount of 25 per cent. This may include, for example:
|
| Occupied exemptions |
Dwellings exempt from Council Tax, which are occupied. This includes:
|
When interpreting the figures, it is important to note that vacant dwellings will not be included here if they are not recorded on Council Tax systems - for example, short-term vacancies which can arise when people move house. In addition, second homes which are let out for more than 140 days per year are not liable to pay Council Tax - they are instead liable to pay non-domestic tax rates. This means that such dwellings are not included here, in either the figures on second homes (Tables 7 to 10), or the total number of dwellings (Tables 2, 9 and 10).
Dwellings and households (Tables 1 and 2)
Summary information on the number of dwellings in different categories is provided by each local authority to the Scottish Government (SG), using the Council Tax Base form, 'Ctaxbase', available from the SG website. The information on the number of dwellings contained in Table 2 is based on these figures.
In order to produce the household estimates shown in Table 1, vacant dwellings and second homes are removed from the figures shown in Table 2. The resulting number of occupied dwellings is then adjusted from September back to June, as the mid-year population estimates and household projections are both based at 30 June each year.
A number of factors can lead to differences between the number of households recorded in Council Tax systems and what was recorded in the most recent census. This can include the treatment of vacant dwellings, shared dwellings, holiday lets, caravans and some communal establishments (such as halls of residence). Previous years' publications have included an adjustment for the difference from the 2001 Census, in order to improve consistency and comparability.
For the 2011 and 2012 data contained in this publication, the same type of adjustment has been applied, but the results use the most recent 2011 Census, instead of the 2001 Census. The household estimates for each local authority are adjusted by the percentage difference between the number of households recorded in the 2011 Census (adjusted to June) and the 2011 Council Tax figures. The same adjustment will be applied to each year's figures in future publications. The size of the adjustment is not the same for all local authorities. In 2011, it varied from a reduction of around three per cent to an increase of around four per cent.
The figures for 2001 to 2010 have also been revised in this publication. An adjustment is added to each year, which is obtained from an amount calculated from the differences in 2001 and in 2011. Each year is adjusted by a slightly different amount from this calculation, which is obtained from straight-line interpolation between the differences found in 2001 and in 2011. A report has been published on these differences and the quality of the estimates from both sources. The 2011 Census Reconciliation Report - Households: Comparison of the 2011 Census household results and the Household Estimates and Projections for Scotland can be found on the NRS website.
Vacant dwellings and second homes (Tables 7 to 10)
Clackmannanshire and Renfrewshire councils cannot separately identify vacant dwellings and second homes. Therefore, these properties are grouped together as one category. In 2012, 3.1 per cent of dwellings in Clackmannanshire and 4.1 per cent of dwellings in Renfrewshire are classed in this way. From the 2001 Census17 , less than 0.2 per cent of dwellings in these areas were identified as second homes, so the total figures have been included under 'vacant dwellings'.
In publications for the years 2010 and 2011, separate figures were not able to be provided for second homes in East Renfrewshire (in Table 9). When comparing these years' figures with earlier and later years, dwellings for 'second homes' should be included in the 'vacant dwellings' category in order to have consistent figures for comparison over time. This year, the council is now able to separately identify these figures again. For 2012, 0.5 per cent of dwellings are classified as 'second homes' in this council, and 1.2 per cent classified as 'vacant dwellings.'
Neighbourhood statistics
The Ctaxbase report, which has been used by NRS to produce household estimates for several years, only provides figures at the local authority level. In order to produce statistics about occupied and vacant dwellings for smaller geographic areas, NRS collects equivalent data at data zone level. Data zones are a standard geography used for a range of statistics. When first created in 2004, the average data zone was designed to contain around 750 people, which is small enough to provide quite detailed local information and can be aggregated to different areas of interest.
The first analysis of this data was included in the 'Estimates of Households and Dwellings in Scotland, 2007' publication (available on the NRS website). Data zone level information on the percentage of dwellings that are occupied, vacant, second homes, entitled to a 'single adult' Council Tax discount, or an 'occupied exemption' is available from the Scottish Neighbourhood Statistics (SNS) website. This information is collected as at September each year to be in line with the Ctaxbase report.
In a number of cases, the totals from each data zone do not exactly match the local authority figures from 'Ctaxbase'. For example, some dwellings on the Council Tax systems do not have postcode information or have invalid postcode information. This varies between local authorities. In 2012, it varied from all dwellings in a council having a valid postcode to around two per cent of dwellings with missing or invalid postcodes. The postcode is used to identify the data zone, so a dwelling without a postcode will not be included in the data zone level figures. In most cases where there are differences, local authorities have confirmed that the Ctaxbase figures will be more accurate, so the data zone figures are constrained to the Ctaxbase totals for each local authority.
A small number of local authorities have told us that the neighbourhood-level total for a particular category is more accurate. In these cases, we use the neighbourhood-level total rather than the 'Ctaxbase' total in both the neighbourhood statistics and local authority household estimates.
There can be variations in the ways that some local authorities classify vacant properties and second homes between different years. This can have a small effect on the percentages of dwellings which are vacant or second homes each year in a local authority.
Prior to 2010, there was some difficulty in extracting full data zone information from the software systems used by East Renfrewshire council, so it was not possible to publish full neighbourhood-level data for this area. However, this was rectified for 2010 data and data zone figures for East Renfrewshire are included in the relevant tables in this publication and are available on the SNS website. Only local athority level figures for East Renfrewshire are available for 2009 and earlier years.
3.2 Dwelling estimates from the Assessors' Portal
The Scottish Assessors are responsible for valuing property for Council Tax purposes. They maintain their web-based Scottish Assessors' Portal, which contains details of every dwelling in Scotland along with its Council Tax band.
NRS uses data from the Assessors' Portal to publish information on the number of dwellings in each data zone in Scotland, along with information about the Council Tax band, type of property and number of rooms. This information is based on an extract of the Assessors' Portal database taken around December - January each year. For 2012, the data was extracted on 7 January 2013.
Summary information on dwellings is included in Tables 3 to 6 of this publication and information for each data zone is available from the SNS website. The total number of dwellings on the SNS website for each data zone is taken from the Assessors' Portal data. We use this source rather than the Council Tax information for the total number of dwellings in a data zone because every dwelling has been assigned a postcode and as a result can be allocated to a data zone.
Definitions of dwelling types
| Category | Description |
| All dwellings | This is the total number of dwellings on the Council Tax valuation list (excluding free-standing private lock-ups and garages). A 'dwelling' refers to the accommodation itself, for example a house or a flat, and includes second homes that are not let out commercially. Caravans count as dwellings if they are someone's main home. |
| Council Tax bands | Each dwelling is placed in one of eight Council Tax bands (A to H), with dwellings in band H being the most expensive. The Council Tax band reflects the Assessor's opinion of open market value, subject to a number of statutory assumptions. Assessors base their opinion of value on the actual selling prices of similar properties which sold around the valuation date of 1 April 1991. |
| Dwellings per hectare | This variable has been calculated by dividing the total number of dwellings by the area in hectares, as determined by a NRS in-house measure. |
| Type of dwelling: |
This information is based on 'attachment' - i.e. the type of property in relation to its degree of attachment to surrounding properties. This information has been aggregated into five categories:
|
| Number of rooms | In the Assessors' Portal, this is defined as the number of habitable rooms (usually bedrooms and living rooms). There may be some differences between different Assessors' areas in the way in which this information is recorded. For example, differences could arise in the treatment of open plan areas, dining rooms, kitchens and kitchenettes. This information on number of rooms may not always represent the most up to date position. Assessors are only able to reflect physical changes and alterations to dwellings once they have been sold and a reconsideration of the banding has taken place. Information on the number of rooms is not available for most dwellings in Shetland. No information is separately available for dwellings with seven or more rooms in Dumfries and Galloway. |
Household and dwelling estimates are drawn from administrative data sources relating to Council Tax. There are limitations in using administrative sources to produce statistics. Small differences can arise in the definitions used for various categories of households/dwellings in the administrative systems used. It is also possible that not all information held on administrative systems is up-to-date. For example, local authorities may not be notified immediately of a change in the circumstances of a household which affects eligibility for a Council Tax discount or exemption. Furthermore, it may take time for changes as a result of new building or demolition to be recorded.
Changes over time in categories of Council Tax discounts and exemptions can occur because a local authority has carried out a review and identified cases where a dwelling has been incorrectly categorised. There can also be variations in the ways that some local authorities classify vacant properties and second homes between different years. This can have a small effect on the percentages of dwellings which are vacant or second homes each year in a local authority.
When using neighbourhood-level (i.e. data zone-level) information on dwellings and households, users should be aware that changes over time can occur at this level not only as a result of new building activity and demolition, but also because of changes related to the postcodes of dwellings. Postcode changes can occur due to improvements made to administrative systems or NRS data cleaning, and re-locating postcodes which were previously allocated to an incorrect neighbourhood. Differences can also occur when postcodes are allocated to a different neighbourhood because the distribution of their population has changed. These differences are likely to be minimal and have only a small effect on change over time, except when looking at small numbers of data zones.
The neighbourhood level collection of Council Tax information is a relatively new data collection. It has seen improvement in data quality and coverage since it began in 2007. This should be noted when making comparisons over time.
Average household size is calculated using the mid-year household estimates, the mid-year population estimates, and communal establishment rates from the 2001 and the 2011 Censuses. The first step in calculating the average household size is to calculate the number of people living in private households ('private household population') rather than in communal establishments, such as student halls of residence, prisons or care homes. This is done by applying the communal establishment rates to the mid-year population estimates to estimate the communal establishment population and subtracting this population from the mid-year population estimate. Communal establishment rates for 2002 and 2010 were estimated from the 2001 and 2011 Census rates. The second step is to estimate average household size by dividing the private household population by the mid-year household estimate. Average household size has been included in this publication 'Estimates of Households and Dwellings in Scotland' for the first time.
3.5 Information on household types from the Scottish Household Survey
The Scottish Household Survey (SHS) is used to estimate the number of households of each type in Scotland as a whole (Tables 12 and 13, and Figures 19 to 21). The sample size of this survey is not large enough to provide reliable information on each household type in each local authority. More information about the Scottish Household Survey is available on the SG website.
The estimates of the number of households of each type obtained from the SHS are adjusted so that the total number of households is equal to the NRS household estimate figure in each year. The SHS figures are rounded to the nearest 1,000.
3.6 Urban/rural classification
The SG produces an urban/rural classification, which is based on settlement size defined by NRS and accessibility based on drive-time analysis. An urban/rural classification is provided for each data zone in Scotland and this information has been used to analyse the data shown in this publication.
This year's publication uses the latest urban/rural classification, the 2011-2012 Scottish Government Urban/Rural Classification, which was published in August 2012.
There are six urban and rural classifications, shown below:
| Scottish Government urban/rural classification | |
| 1 Large Urban Areas | Settlements of over 125,000 people. |
| 2 Other Urban Areas | Settlements of 10,000 to 125,000 people. |
| 3 Accessible Small Towns | Settlements of between 3,000 and 10,000 people, and within a 30 minute drive time of a Settlement of 10,000 or more. |
| 4 Remote Small Towns | Settlements of between 3,000 and 10,000 people, and with a drive time of over 30 minutes to a Settlement of 10,000 or more. |
| 5 Accessible Rural | Areas with a population of less than 3,000 people, and within a 30 minute drive time of a Settlement of 10,000 or more. |
| 6 Remote Rural | Areas with a population of less than 3,000 people, and with a drive time of over 30 minutes to a Settlement of 10,000 or more. |
Source: Scottish Government Urban/Rural classification 2011-2012 of the SG website.
3.7 Scottish Index of Multiple Deprivation
The Scottish Index of Multiple Deprivation (SIMD) is produced by the SG to identify concentrations of deprivation across Scotland in a consistent way. It is based on 38 indicators in seven domains: Current Income, Employment, Health, Education Skills and Training, Geographic Access to Services, Housing and Crime. A SIMD rank is produced for every data zone in Scotland. Based on this, the SIMD deciles are produced, from one (most deprived) to ten (least deprived). This information, from the 2012 SIMD, has been used to analyse the data shown in this publication.
This publication uses the revised version of the 2012 SIMD. More information about the SIMD is available from the SG website.
3.8 Strategic Development Plan (SDP) areas and National Parks
In 2009, NRS produced for the first time household projections for Scotland's Strategic Development Plan (SDP) areas and National Parks. These were 2006-based projections. In 2012, NRS published 2010-based projections for these areas. These Household Projections can be found, along with information on the areas covered by the SDP areas and National Parks on the NRS website.
SDP areas cover the four largest city regions around Aberdeen, Dundee, Edinburgh and Glasgow:
Glasgow and the Clyde Valley Strategic Development Plan Area (Glasgow and the Clyde Valley SDP area)
Aberdeen City and Shire Strategic Development Plan Area (Aberdeen City and Shire SDP area)
Edinburgh and South East Scotland Strategic Development Plan Area (SESplan SDP area)
Dundee, Perth, Angus and North Fife Strategic Development Plan Area (TAYplan SDP area)
The household and dwelling information presented in this publication for SDP areas is built up from local authority level information, where the entire local authority is within SDP area boundaries, and data zone level information, where this is not the case.
Scotland has two National Parks: the Loch Lomond and the Trossachs National Park and the Cairngorms National Park.
National Park estimates of household and dwellings are built up from data zone level information.
Data zone boundaries do not exactly match SDP area and National Park boundaries. For the purposes of these estimates (as with the household projections for SDP areas and National Parks), data zones are included or excluded based on the location of the data zone centroid as determined by the SG. This is a standard approach for assigning the population of a smaller geographical area to a larger one. The data zone centroid does not represent the geographical centre of a data zone but is rather a representation of the population weighted centre (or, to put it more simply, the population 'centre of gravity') of the area. In this publication, a data zone is allocated to a National Park if its population centroid lies within the Park boundary.
In October 2010, the boundary of the Cairngorms National Park was extended to include some areas of northern Perth and Kinross including Blair Atholl. Although this change increases the number of data zones which fall at least partly within the Park boundary, the population centroids of these additional data zones lie outwith the boundary. Therefore, they are excluded for the purposes of the figures shown in this publication. The data zones used for SDP areas and National Parks in this publication are therefore the same as those in previous publications on the NRS website.
Further information about SDP areas, including maps showing the boundaries of each SDP area is available from the Scottish Government (SG) website.
Statistics about dwellings and households are used mainly for informing local authority decisions about housing need and the provision of services (including housing, planning waste collection and community care). The statistics feed into local authorities' development plans, including assessments of housing need and demand both at present and for the future. Some local authorities use the statistics as the baseline for producing their own projections of the future number of households.
The statistics are also employed in land use allocation and planning, and in land use and transport models. Small area statistics on dwellings and households are used by Scottish Water to assess demand for water and sewerage services. They have also been used in risk analysis by Fire and Rescue services, to provide information on housing in rural areas (including second homes and empty dwellings) and to inform projections of the future size of school rolls. In addition, they are often used to produce profiles of small areas to increase local knowledge.
On the Scotland's Census website, release 1B of Scotland's Census 2011 in March 2013 included national and local authority household estimates. The NRS household estimates were used to help quality assure this data and to reconcile any differences arising between the two sources. A report has been published on these differences and the quality of the estimates from both sources. The 2011 Census Reconciliation Report - Households: Comparison of the 2011 Census household results and the Household Estimates and Projections for Scotland can be found on the NRS website. Forthcoming releases from the census will also be compared to the NRS household estimates.
Household estimates are used as the denominator for other statistics, such as the percentage of households receiving benefits. They are also used in various forms of research.
NRS uses household estimates in the production every two years of projections of the future number of households, which are available in 'Household Projections for Scotland' (available on the NRS website). Household estimates and projections (for Scotland and the UK) are used directly and indirectly in the production of certain statistics contained within the Scottish Government's annual Government Expenditure and Revenues Scotland (GERS) publication and the quarterly Scottish National Accounts Project (SNAP) PDF release, both of which can be found on the SG website.