Main data source

  • Office for National Statistics Product Sales and Trade (ProdCom) reports, (ONS, 2001).

What is ProdCom?

ProdCom (Products of the European Community) is a survey of manufactured products regulated by the European Union (EU). The names and descriptions of the products covered are standardised to enable comparability between member states. Data is collected on value (sales) and volume (units) for over 4,800 products assigned to 200 industries. Over 3,000 companies and 200 industries are surveyed yearly and others are surveyed on a quarterly basis. The Office for National Statistics collects this information for the UK (ONS, 2001).

Data availability and quality

There was little primary data available on product manufacturing in the South West, so UK ProdCom data was proxied to derive an estimate of product flows in the South West.

Calculation and proxy measures used

In its published format, ProdCom data could not be used directly, but needed manipulation before it could be used to estimate product flows through the South West. The two main stages were:

  • The production of a standardised UK data set.
  • The application of proxy factors to scale UK figures to the South West.

Sales data from Prodcom was used to represent production data for the products in this section.

Production and validation of UK ProdCom sheets

ProdCom is primarily economic data tracking the value of products throughout different stages of the manufacturing process. When taking actual tonnage of these products, double counting is likely to occur. Resources flow between different industries, so that a final product of one stage could go on to be used in the manufacturing process of another product. For example, iron can be used in the manufacturing of automotive parts, which in turn are incorporated into cars. ProdCom would report this iron twice, once in a vehicle part and once in the car, thus double counting its weight. This issue was overcome by labelling all products as either intermediate (vehicle parts) or final product (car). Only final products were included in the total volume to avoid double counting.

Due to data gaps in ProdCom, there were instances where net supply figures were negative. This could occur if sales data was unavailable or suppressed, giving a larger volume of exported products than imports (see example 1). Clearly it is impossible to consume a negative volume of products, but because sales and import data gaps balance export data gaps in ProdCom, the total net supply figures were accurate. SIC 19: 'Leather luggage, handbags & footwear' was the only sector where the total consumption figure calculation gave a negative result. This was because a large amount of production data was suppressed or unavailable, leading to an underestimate of supply. Because SIC 19 represented only a small fraction of consumption in the South West (around 3%), the negative figure was included in the total products figure for the South West.

'Weight per item' conversion factors were researched and applied to convert Prodcom data into tonnes where it was originally supplied in other units.

Example 1

PRA 33.101739: Orthopaedic appliances and other fracture appliances INCLUDING – parts and accessories – orthopaedic made to measure footwear – orthopaedic appliances for animals.

The Sales figure for this sector is not available.

Net supply (N) = Sales (SL) + Imports (I) – Exports (E)

= n/a + 1,187 – 1,551

= -364 tonnes

The application of proxy factors to scale UK figures to South West level

After calculating the total UK mass of products sold, imported, exported and consumed (net supply) for each sector, each one was scaled to South West level using economic conversion factors. The ECON-I tool (University of Plymouth, 2003) provided detailed economic data for all SIC sectors (1-36) including GVA and full time employees (FTE). Example 2 demonstrates this method of proxying.

Example 2

PRA 34.102230: Motor vehicles with a petrol engine greater than 1500cc.

N UK = SL UK + I UK - E UK

= 932,104 + 1,181,465 – 545,664

= 1,567,905 (tonnes)

Therefore, 1,567,905 tonnes of motor vehicles were supplied in the UK in 2001. The motor vehicle manufacturing industry (SIC 34.1) in Great Britain and the South West employed 221,773 and 12,401 workers respectively (University of Plymouth, 2003). Therefore 5.59% of full time employees in this sector are based in the South West. This percentage was used as a proxy to calculate South West motor vehicle production:

N SW = N UK x Proxy

= 1,567,905 x 5.59%

= 87,645 (tonnes)

Net supply was derived using economic factors appropriate to the sector, for production, imports, exports and net supplies for all products listed in ProdCom. The results were used to derive a total resource flow of products for the South West.

Data recommendations

  • ProdCom data is presented in PDF and MS Word format. It would be easier to extract and manipulate this data if it were published in Excel.

ProdCom only presents data for the UK as a whole. Regional data would be more appropriate for a study of this kind.