1 Handbook on Population and Housing Census Editing Department of Economic and Social Development United Nations Statistics Division Studies in Methods, Series F, No.82

2 Purpose of Handbook n No census data are ever perfect n Changes are made -- little documentation n Promote communication between subject specialists and programmers n “Cookbook” of suggestions -- presents possible resolutions n But country edit teams must decide

3 Major Elements in a Census n Preparatory work n Enumeration n Data processing -- keying, editing and tabulations n Building data bases and dissemination n Evaluation of results n Analysis of results

4 Errors in Census Process n Coverage Errors n Questionnaire Design n Enumerator/respondent errors n Coding errors n Data entry errors n Computer editing errors n Tabulation errors

5 Editing in Historical Perspective n Before computers: manual editing n With computers: Increased complexity n Automated changes n Generalized editing packages n New philosophies of editing n Personal computers n Appropriate levels of computer editing

6 Editing Team n Appropriate internal subject matter specialists n Computer Programmers n Work together as a team n Edit Specs as means of communication n Outside experts -- academicians n Outside experts -- private sector

7 WHAT CENSUS EDITING SHOULD DO 1 Give users measures of the quality of the data 2 Identify the types and sources of error, and 3 Provide adjusted census results

8 Sample table with & without unknowns

9 Table showing trends with unknowns

10 Basics of Census Editing n Systematic inspection and change (not always correction) n Fatal edits -- invalid or missing entries n Query edits -- inconsistencies n Must preserve the original data as much as possible n Quality enumeration more important than editing n Edit does not improve data quality -- makes more esthetic n Team must determine how far to do

11 More of Basics n Over-editing is harmful n Treatment of unknowns n Spurious changes n Determining tolerances n Learning from the edit process n Quality assurance n Costs of Editing n Imputation n Archiving

12 How Over-editing is Harmful n Timeliness n Finances n Distortion of true values n A false sense of security

13 Editing Applications n Manual versus automatic correction n Guidelines for correcting data n Validity and consistency checks n Methods of correcting and imputing data n Other editing systems

14 Manual versus Automatic Correction n Manual correction: takes a long time and very subject to error n Automatic correction: faster and consistent. n Not necessarily correct, just consistent. n Can look at many variables at the same time n Can keep an audit trail

15 Guidelines for Correcting Data n Make the fewest required changes possible to the originally collected data n Eliminate obvious inconsistencies among the entries n Systematically supply entries for erroneous or missing items by using other entries for the housing unit, person, or other persons in the household or group n When appropriate, use “not reported”

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17 Validity and Consistency Checks n Top-down editing approach n Multiple variable edit n Coding considerations

18 Methods of Correcting and Imputing Data n Change to unknown n Static or “Cold Deck” imputation n Dynamic or “Hot deck” imputation

19 Hot Deck Imputation n Geographic considerations n Use of related items n Sequence of the items n Complexity of the matrices n Standardized hot decks n Size of hot decks -- too big, audit trail, too small, difficult items

20 Language Edit n If this is the head and language is missing, first look for someone else in the house with language, and assign that. n If this is the head without language, no one else has language, use neighboring head of similar characteristics to assign a best guess. n If this is someone else in the house and language is missing, assign the head’s language.

21 Language Edit: Within House

22 Language Edit: Imputed House

23 THANK YOU Everyone come to your census!

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