1. Harvard Center for Population and Development Studies1 Census Editing and the Art of Motorcycle Maintenance Michael J. Levin Center for Population and Development Studies Harvard University Michael.levin@yahoo.com

2. Harvard Center for Population and Development Studies2

3. 3 The Census Process Data collection Capture Editing Tabulation and Dissemination Archiving

4. Harvard Center for Population and Development Studies4 History of census editing Early years – manual or nothing Computers Within record editing Between record editing Hot decking

5. Harvard Center for Population and Development Studies5 What is editing Editing is the systematic inspection of invalid and inconsistent responses, and subsequent manual or aurtomatic correction according to pre-determined rules. The editing team!!

6. Harvard Center for Population and Development Studies6 Why edit? Edited vs unedited data Always preserve original data Consider the users!!

7. Harvard Center for Population and Development Studies7 Table 1. Sample population by 15-year age group and sex, using unedited and edited data

8. Harvard Center for Population and Development Studies8 Initial data sets contain errors How over-editing is harmful  Timeliness  Finances  Distortion of true values  False sese of security

9. Harvard Center for Population and Development Studies9 What we have to look out for Treatment of unknowns Spurious changes Using tolerances Learning from the editing process Quality assurance Costs of editing

10. Harvard Center for Population and Development Studies10 Types of Correction  Manual correction Names Sex  Automatic correction Assign an unknown Assign a value Impute a value

11. Harvard Center for Population and Development Studies11 Types of editing  Top Down The usual way Is simple and straight forward  Multiple-variable editing approach Uses more information Is likely to be a better guess

12. Harvard Center for Population and Development Studies12 Two parts of a national edit Structure editing Content editing

13. Harvard Center for Population and Development Studies13 Methods of Correction and Imputation  When imputation is not needed – toggling sexes  Static imputation – cold deck technique  Dynamic imputation – hot deck technique

14. Harvard Center for Population and Development Studies14 Goals of the edit Imputed household should closely resemble failed edit household Imputed data should come from a single donor person or house resembling donee Equally good donors should have equal chances

15. Harvard Center for Population and Development Studies15 Figure 1. Sample editing specifications to correct sex variable, in pseudocode

16. Harvard Center for Population and Development Studies16 Hot Deck Geographic considerations Use of related items Order of the items changes the matrices Complexity of the imputation matrices

17. Harvard Center for Population and Development Studies17 In developing hot decks Imputation matrices – structure of the matrices Standardized imputation matrices Seeding the decks Big, but not too big Understanding what the matrix is doing When the matrix is too small … Occupation and industry!!

18. Harvard Center for Population and Development Studies18 Aids to checking edits 1. Listings 2. Writing whole households before and after with changes 3. Frequency matrices

19. Harvard Center for Population and Development Studies19 Figure 4. Example of a listing summary for Malawi 2008 Census [LISTING]

20. Harvard Center for Population and Development Studies20 Figure 5. Example of a listing summary for Lesotho 2006 Census [LISTING]

21. Harvard Center for Population and Development Studies21 Figure 8. Example of a write listing for Ethiopia 2007 Census [WRITE]

22. Harvard Center for Population and Development Studies22 Figure 10. Example of a frequency distribution for Sudan 2008 Census [FREQUENCY]

23. Harvard Center for Population and Development Studies23 Figure 11. Example of a frequency distribution for additional edit for Zambia 1990 Census [FREQUENCY]

24. Harvard Center for Population and Development Studies24 Other considerations Running the edit three times: seed, run, check Saving original responses Imputation flags

25. Harvard Center for Population and Development Studies25 Conclusions Edits part of the series of census procedures Usually more for aesthetics than technical enhancement Hardware and software changing rapidly The revolution continues!