1 ( o ns) occupational coding in practice: from the 1981 to 2001 census of population tessa staples...
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Occupational coding in practice: from the
1981 to 2001 Census of Population
Tessa Staples
June 2004
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Census Occupational Coding 1981 to 2001
Transition
1981 Manual or Clerical coding
- 10% Sample
1991 Computer assisted coding
- 10% sample
2001 Automated coding(automatic coding and interactive
coding)
- No sample processing
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Census Occupational Coding 1981 to 2001
Census processing
1981 Managed in-house
- Titchfield and Bootle offices
1991 Managed in-house
- Titchfield and Hillington offices
2001 Contracted to Lockheed Martin
- Widnes office
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Census Occupational Coding 1981 to 2001
Classifications and coding frames1981 Classification of Occupations 1980
351 operational codes
1991 Standard Occupational Classification (1990)
480 component codes
2001 Standard Occupational Classification 2000
353 unit group codes
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Census Occupational Coding 1981 to 2001
Information needed by the coding index
CO80 SOCSOC
1990 2000
Job title Job description
Industry of employer
Professional qualifications Employee/Self-employed Major organisation
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Census Occupational Coding 1981 to 2001
Occupation coding index
Principles and layout style were devised
for efficient clerical coding• Simple look-up• Quicker coding• Greater coding consistency
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Census Occupational Coding 1981 to 2001
Occupation coding index
Using indexing words
Warehouse manager
Warehouse salesman
Warehouse cleaner
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Census Occupational Coding 1981 to 2001
Occupation coding index
Using indexing words
Warehouse manager = 1162
Warehouse salesman = 7111
Warehouse cleaner = 9233
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Know your onions - at the check-out
“Why can’t I find onion in the list?”
Census Occupational Coding 1981 to 2001
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Know your onions - at the check-out
Because listed as
‘Brown onion’
Census Occupational Coding 1981 to 2001
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Census Occupational Coding 1981 to 2001
Occupation coding index
Reverse word order
In response - Pest control inspector
In index - Inspector, control, pest
• Brings together variations on the indexing word in one place
• Enables use of ‘default’ entries
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Census Occupational Coding 1981 to 2001
Occupation coding index
Qualifiers to indexing words
• Occupation qualifiers• Additional qualifiers • Industry qualifiers
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Census Occupational Coding 1981 to 2001
Occupation coding index
List for Gateman
8219 Gateman, bridge
8219 Gateman, dock
8219 Gateman, flood
8219 Gateman, lock
8216 Gateman (coal mine)
8219 Gateman (docks)
9249 Gateman (entertainment)
8216 Gateman (railways)
8219 Gateman (waterways)
9241 Gateman
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Census Occupational Coding 1981 to 2001
Occupation coding index
List for Chain makers
5495 Maker, chain (metal, precious)
8129 Maker, chain (metal)
5211 Maker, chain (metal trades, forging)
8129 Maker, chain (metal trades)
8113 Maker, chain (textile mfr)
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Census Occupational Coding 1981 to 2001
Occupation coding index
Power of the default entries
(from use of index in 1991 Census)
Cleaner 35.9%
Cleaner, school 8.0%
Cleaner, office 6.4%
Cleaner, window 6.0%
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Census Occupational Coding 1981 to 2001
Organisation - 1981 and 1991 CensusesHeadquarters
• Instructions, coding indexes (amendments), training exercises
• Analysis of coding queries
• Independent quality control - ‘blind’ checking
• Audit inspection - 1991 only
Teams coding occupation and employment status
• Supervisors - answered coding queries
• Coders
• Query writers - 1991 only
• Query resolvers - 1991 only
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Census Occupational Coding 1981 to 2001
Organisation - 2001Census
Headquarters - ONS • Guidance, master copy of coding index (amendments),
tuning data (thousands of coded job titles in natural word order)
• ‘Second stop’ query resolvers• Sight checking
Teams coding occupation (some cross-topic training)
• Supervisors • Frontline coders• Expert coders - ‘First stop’ query resolvers
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Census Occupational Coding 1981 to 2001
1981 Census coding
Coders used• Census specific coding instructions
– also on an A3 sized flowchart• Modified Occupation Coding Index
– notes on coding– most industry qualifiers converted to
Census industry codes
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Census Occupational Coding 1981 to 2001
1981 Census Modified Occupation Coding IndexGateman;
bridge … … … … … 338
dock … … … … … 338
flood … … … … … 338
lock … … … … … 338
Gateman- … … … … … 140
503 … … … … … 321
742 … … … … … 321
746, 749 -
waterways .. … … … 338
750 … … … … ... 338
801,802 … … … … 165
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Census Occupational Coding 1981 to 2001
1991 Census coding
Coders used• Census specific coding instructions
– also on an A3 sized flowchart• ‘Computer Assisted Census Occupation
Coding’ (CACOC)– displayed the modified occupation
coding index on the screen of a stand-alone PC
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Census Occupational Coding 1981 to 2001
1991 Census coding
CACOC• developed by Census IT staff at General
Register Office for Scotland (GROS)• similar to the Australian coding tool, ASCO• not to reduce the number of coders but
achieve better coding consistency (?)
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Census Occupational Coding 1981 to 2001
1991 Census - CACOCOCCUPATION TITLE: GATEMANGateman
bridgedockfloodlock503742746,749
waterways750801,802Except above
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Census Occupational Coding 1981 to 2001
1991 Census - CACOCOCCUPATION TITLE: GATEMANGateman
bridgedockfloodlock503742746,749
waterways750801,802Except above
420
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Census Occupational Coding 1981 to 2001
2001 Census• Capture and coding contracted to
Lockheed Martin• LM chose ACTR (Automated Coding by
Text Recognition) as the coding tool• ONS’s Census staff specified contract and
provided much support to LM• Processing operation subcontracted to ICL• ICL’s Knowledge Pool produced the
training material
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Census Occupational Coding 1981 to 2001
2001 Census - Occupation coding screen
Image of census form Job title on record
Qualifications indicator box
Code Unit group title
Choice list
Accept
Industry code SIC group title
Not codeable To expert
Enter text for search
Search
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2001 Census - Occupation Coding Job title on record = Cellzzman
Industry code on record = 51
Text entered by coder = CELLARMAN wineSOC SIC Text
9149 159 Cellarman <wine mfr.>
9149 51 Cellarman <wine merchants>
8111 159 Cellarman
9225 551 Cellarman
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9225 BAR CELLARMAN
9225 BAR/CELLAR SUPERVISOR
9225 BAR STAFF/CELLARPERSON
Census Occupational Coding 1981 to 2001
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Number of occupation coding queries
1981 - 37,000 Apparently too few
1991 - 175,000 (in 54 metal trays on three trolleys)
2001 - 33,000 As sent to ONS
Revising the coding index during processing 1981 1991
2001
Number of times the index was revised 6 4 10
Total number of changes 131 393 311
Census Occupational Coding 1981 to 2001
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Independent quality control reported
1981 Census - 4.9% error rate
1991 Census - 5.5% error rate
2001 Census• Contract specified as acceptable
12.0% error rate• Lockheed Martin reported
8.9% error rate• ONS assessed from sight checking
10.96% error rate
• Automatic coding throughput
72.2%
Census Occupational Coding 1981 to 2001