1. 1 Health Statistics & Informatics WHO practices in imputation and estimation Conference on Data Quality for International Organizations Rome, Italy, 7-8 July 2008-05-28 Carla AbouZahr Coordinator, Statistics, Monitoring and Analysis World Health Organization Geneva

2. 2 Health Statistics & Informatics Types of health statistics Unadjusted health statistics derived directly from primary data collection with no adjustments or corrections.

3. 3 Health Statistics & Informatics

4. 4 Types of health statistics Unadjusted health statistics derived directly from primary data collection with no adjustments or corrections. Adjusted health statistics corrected to deal with known biases, use of indirect techniques.

5. 5 Health Statistics & Informatics

6. 6 Types of health statistics Unadjusted health statistics derived directly from primary data collection with no adjustments or corrections. Adjusted health statistics corrected to deal with known biases, use of indirect techniques. Predicted health statistics based on a model relating the quantity of interest to covariates. – Forecasting: past relationships to predict future – Farcasting: missing primary data

7. 7 Health Statistics & Informatics

8. 8 Source: Gareth Jones WHO/UNICEF database

9. 9 Health Statistics & Informatics Source: Christopher Murray Institute for Health Metrics and Evaluation

10. 10 Health Statistics & Informatics Sources of data for global mortality estimates (circa 2004) Child mortality: q5 Adult mortality: 45q15 Source: WHO Indirect methods problematic for adult mortality Birth histories, Indirect methods;

11. 11 Health Statistics & Informatics

12. 12 Health Statistics & Informatics WHO principles for imputation Standard four-step procedure for estimation – a high-quality accessible database; – an independent peer review group; – published methods of estimation; margins of uncertainty – internal WHO clearance by HSI Country consultation – iterative process between Member States, WHO country and regional offices and headquarters – feedback on quality of data collection and reporting; strengthening country capacity to reproduce, produce and use estimates.

13. 13 Health Statistics & Informatics External advisory bodies Disease-specific M&E reference groups – Include agencies and academic experts – Address coordination issues – Develop "best estimates": <5, maternal mortality, coverage of interventions Advisory Committee on Health Monitoring and Statistics (ACHMS) – Independent outside experts – Gives inputs to WHO on its work, including Global Burden of Disease, World Health Statistics. – Advises DG on scientific and technical issues.

14. 14 Health Statistics & Informatics Summary and conclusion WHO use of imputation: – Correction for definitional differences, application of WHO standards, known biases – Production of regional aggregates – Generation of missing values for countries Recommendations for CCSA – General principles for imputation – Methods context and subject specific – Transparency and replicability – Country endorsement of methods not values