1. PRODCOM SURVEY IN THE UNITED KINGDOM

2. Areas to be covered: Why we conduct the PRODCOM survey and who uses it
Team structure
How we collect and validate our data
Statistical processes
Publication processes

3. Purpose of the PRODCOM survey
Uses
EU regulation
Compilation of National Accounts
To aid Trade Associations in research and helping manufacturers identify market opportunities
Environmental issues
A sampling frame for PPI
Chain linking of PPI

4. Structure of the PRODCOM survey
Split into three sections.
Survey Processing Centre
Editing and Validation
Results
Analysis
and Publication

5. Collecting Data – Sample Design (1)
The UK uses a sample survey and grosses to provide estimates of the UK manufacturing population
Annual sample size of approximately 21,500 using Permanent Random Numbers sampling, post stratification
Stratification is the grouping together of similarly homogenous units
The UK PRODCOM Survey stratifies by NACE class and employment size to give a range of 5 strata

6. Collecting Data – Sample Design (2)
Stratum
Employment
Sample
Universe 1
0 – 9
1,800
105,700 2
10 – 19
5,600
13,500 3
20 – 49
7,100
9,800 4
50 – 99
3,500
3,800 5
100+
Total
21,800
136,600

7. Collecting Data – Sample Design (3)
Businesses within stratum 1 can only be selected once for any survey
Then have a rest period of three years
Known as the Osmotherly guarantee.
Each NACE has an employment ‘cut-off’ which is either, 20, 50 or 100.
All businesses with employment above cut-off are selected for PRODCOM each year
For rest of sample, there is a 10% forced rotation
Businesses are selected for 10 years before a break

8. Collecting Data – The Questionnaire (1)
Paper questionnaire tailored to meet the business need
Newly sampled businesses telephoned in advance and product questionnaires added prior to dispatch
Alternatively new selected write in their product info on first selection
In Section B, the business will describe their products, provide a description and CN and the value of their production

9. Collecting Data – The Questionnaire (2)
Analysts ‘code out’ product descriptions to appropriate PRODCOM codes
The coding of the product is confirmed with the business by telephone and a volume for each product sought
In the absence of volume information, where there are other returns for the same product, a ‘batch construction’ can be inserted

10. Collecting Data – The Questionnaire (3)
Once a business has confirmed their production items, these are then added to their questionnaire in future surveys
The questionnaire asks for ‘other income’ in Section C and the addition of values in Sections, A, B and C should equal ‘Total Turnover’ in Section D
On receipt of the questionnaire, these are scanned in to the system

11. Statistical Processes – Micro data Editing/Validation
The data is then tested against numerous credibility criteria
Validation is performed at product level and credibility gates are set individually for each product
Selective editing method is applied - ranks failing respondents by ‘impact’ on final estimates

12. Statistical Processes - Outliers
Correct response that is not representative of the sample - undue influence on the estimate
This extreme response is excluded from the calculation of industry sales per head
Automatic Outlier – If more than 10 businesses making a product, the top and bottom 5% are trimmed in sales per head calculation
Manual Outlier – Businesses that are manually marked as an outlier by the results analyst at the results processing stage

13. Statistical Processes - Imputation
If business A returned last year, but non-responder this year
For each business that returned a value for a product both this year and last, calculate the growth in sales
Apply the average growth (trimmed) to the value returned by business A last year
This is the imputed value for business A
Assumes non-responders have similar characteristics to those who have responded in both years

14. Statistical Processes - Estimation
As PRODCOM UK is a sample survey, the returned information is used as a basis for estimation for the entire UK manufacturing population
Total UK manufacturer sales = Total returned sales of companies (including imputed & constructed) + estimated sales of companies who have never returned their form or were not in the sample
Non-linear estimator – sales per head, product propensity

15. Statistical Processes – Output Editing/Validation (1)
Grossed Estimates Results Checking
Each question is put the through the estimation procedure in the SAS results system.
SAS compares data and looks for:
Large year on year changes
Consistency of unit values
Revisions of previous years data
Each of the above has failure gates. If these are breached then the product/industry are investigated by the analyst.

16. Statistical Processes – Output Editing/Validation (2)
Possible reasons for failures:
Entrance and departure of businesses from a sample
New business causing high grossing
Business misreporting sales
Figures given in £ rather than £000s
Genuine increases
Businesses classified to the wrong industry

17. Statistical Processes – Disclosure
All estimates are tested for their contribution to a product and are tested using a dominance threshold disclosure model
Where businesses dominate production of a product, a letter is sent to them asking for permission to publish
If permission is denied, then the estimate is suppressed

18. Publications (1)
The UK publishes its estimates about 30 June for the previous reference year, marking them as ‘Provisional Results’. These results are transmitted to Eurostat on same day
An ‘Intermediate’ set of results are then published in December, whereby at the same time, the previous years ‘Intermediate’ become ‘Final’. After each publication, results are transmitted to Eurostat

19. Publications (2)
A Statistical bulletin and accompany Excel data files are placed on the ONS website on the day of publication.
For each product, the corresponding CN number is published, along with Intra and Extra EU imports/exports

20. Publications (3)

21. Code of Practice for Official Statistics
UK Statistics Authority – independent body, directly accountable to parliament
Promote and safeguard the production and publication of official statistics
Assess statistics against Code of Practice – designate as National Statistic
PRODCOM assessed June 2012 – designated subject to requirements being met, eg:
User engagement; Revisions; Review quality assurance procedures; Improve commentary for user interpretation; Investigate the use of other data sources