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Construction output in Scotland. Stephen Curtis, Office for National Statistics. Structure of the talk. The register and the sample What information do we get? What do we produce for the UK? How do we use our information to produce data for Scotland? How reliable are the figures?.
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Construction output in Scotland Stephen Curtis, Office for National Statistics
Structure of the talk • The register and the sample • What information do we get? • What do we produce for the UK? • How do we use our information to produce data for Scotland? • How reliable are the figures?
Coverage Our surveys cover: • Great Britain • Construction, as in the Standard Industrial Classification, except SIC 41.1 (development of building projects)
The register • To December 2009 was the Builders Address File (BAF) • From January 2010, has been the Interdepartmental Business Register (IDBR) Numbers of businesses *of which, Scotland 15,732 (=7.0%)
Sample sizes Sample of 7,800 construction businesses: • Target for each set of results is for at least 70% of forms to be back; 80% by value of register turnover. Achieved. *= 50.2% by turnover
What information do we get? • Up to December 2009, BIS obtained figures of output (quarterly) and new orders (monthly). For new work output there was only one question. For repair and maintenance there were 4 categories • From January 2010, ONS has obtained figures of output (monthly) and new orders (quarterly). New work output is now split into 6 categories; repair and maintenance into 5 (infrastructure added)
What the output survey measures • Output, not turnover (excludes sub-contractors) • Output of the construction industry, not construction output. Will exclude: De minimis output Businesses not classified to construction Most direct labour departments Development of building projects
UK data • From these questionnaires we can (and do) measure directly: • The value of output. • The value of new orders obtained, in total, by region, and by type of activity. Both sets of figures are then deflated and seasonally adjusted. (Output is only seasonally adjusted quarterly).
Regional data • For new work, we have no direct information on regional output • For new orders of £100,000 or more: we do have information about location of the work • For new orders under £100,000: we assume they are located in the region of the firm’s address • We can make assumptions about how long these orders take to fulfil • Those assumptions are based on surveys from 2005-2007
Location of construction work New orders, Q4 2011, £ million
Fulfilling new orders Proportions of all the work on the order “N” is the quarter that the new order arrives; N+4 would be four quarters (one year) later, and so on
New orders, Scotland £ million
Output, Q4 2011, Scotland £ million Total = £ 1,080 million Note: because the new orders source largely uses the location of the building work, this mainly represents some form of output in Scotland, not necessarily output by Scottish businesses.
Other regions We then undertake the same calculation for each of the other regions of Great Britain We compare the aggregate for all regions taken together with total output directly from the construction survey The total output figures first published for Q4 2011 were:
Published output, Q4 2011- new work only £ million Total new work = £ 19,757 million
Repair and maintenance Value of new work, Q4 2011 = £19,757m Repair and maintenance = £11,185m Total, Q4 2011 = £30,942m So, new work = 64% of the total; repair and maintenance = 36%
Repair and maintenance by region • Repair and maintenance data are collected in the output survey • Assumed that repair and maintenance occurs in the region where the firm is based • So, for example, all repair and maintenance in Scotland is assumed to be undertaken by firms with Scottish addresses • No system of lagging new orders is needed
Deflation • We often want to know not only the current value of building work, but whether the output of the construction industry is growing or shrinking in “real terms” • To do that, we divide the current price amounts by an indicator of how prices have moved in the period (a “deflator”) • We only deflate data for GB as a whole
Construction industry deflators • Are obtained from the Building Cost Information Service (BCIS) • Are of two types: output deflators and tender price deflators • Are used for Great Britain and for every region (by type of work)
Output price deflators * Derived from: public housing R&M = 124.0; private housing R&M =143.7; other categories of R&M = 114.7
Seasonal adjustment • We use the standard ONS method for seasonal adjustment, X-12 ARIMA • Seasonal adjustment is applied individually to each type of work (public housing, private housing etc) • Seasonal adjustment of total GB output is the sum of the component series • Regional figures are not seasonally adjusted
