Project Procedures

Timelines for 2009 (6th) data set:  
Detailed procedures for project: Standard Operating Procedures (Feb 2009)


Timelines for preparation of 2009 (6th) data set:


Expected time for completion


Data specification and request

  • Addition of new variables / codes to data specifications
  • Distribution of data specifications and request for data to centres.
    The request is for data for all patients ever seen for care at a centre

6 weeks


Checking general integrity of data from sites (not of individual records)

  • Recode/manipulate centre-specific data so that it conforms with data specifications
  • Tabulate all variables to identify obvious errors
  • Check of new data against previous data submission for each centre
  • Resolve any problems arising from above with local data manager
  • Clean ART data from each centre via SAS program: includes removal of overlapping datees and short breaks (<14d)

3.5 months


Import of data into database

  • Prepare data files as tab delimited text files, with dates in dd/mm/yyyy format, and include leading zero's
  • Import data into database

3 weeks


Data cleaning of individual records

  • Print out within-centre data queries and consistency checks using pre-existing queries and reports at MRC
  • Liaise with data managers/assistants/research nurse or visit centre to resolve errors
  • Individual edits applied to the database (maintains audit trail)

2 months


Notify centres:

  • send summary of centre-specific data and the results of the cleaning process i.e how many inconsistencies identified and resolved
  • feedback results of data checks for centres to update their local database

1 week



  • Run de-duplication program
  • Manually resolve any ambiguous matches
  • Merge demographic, AIDS, ART and other data files

6 weeks


Data export

  • Export data as text files to study statistician
  • Final SAS manipulation of files (by study statistician) to resolve outstanding data quirks
  • Export selelcted data to other statisticians as required
  • Notify sites that they may have an export of their own (cleaned) data if required

1 month


Total time for dataset prepation 9 months  


Detailed description of UK CHIC procedures

See Appendix 1 in Standard Operating Procedures