WORLD HEALTH ORGANIZATION VACCINATION COVERAGE CLUSTER SURVEYS: REFERENCE MANUAL Version 3 WORKING DRAFT Updated July 2015 Table of Contents List of boxes, figures and tables ........................................................................................................... v Abbreviations .................................................................................................................................... vii Preface ................................................................................................................................................ 1 1. Introduction ................................................................................................................................. 3 1.1. Why vaccination coverage is assessed ......................................................................................... 3 1.2. Methods for measuring vaccination coverage ............................................................................. 3 1.3. Cluster surveys: a practical survey method for reliable results if designed appropriately and excellent quality control is done ................................................................................................... 5 1.4. Changes to previous methods and materials ............................................................................... 6 2. Design the sample structure of the survey .................................................................................. 10 2.1. Convene a survey steering group ............................................................................................... 11 2.2. Discuss the purpose of the survey .............................................................................................. 11 2.3. Identify primary questions that affect survey design and sample size ...................................... 12 2.4. Define the target population ...................................................................................................... 13 2.5. Set inferential goals .................................................................................................................... 14 2.6. Select a survey design ................................................................................................................. 15 2.7. Calculate the required sample size ............................................................................................. 16 2.8. Draft an analysis plan, table shells and report figures ............................................................... 24 2.9. Budget for the survey and estimate the timeline ....................................................................... 24 2.10. Evaluate affordability and timeliness ......................................................................................... 27 2.11. Implications of adding routine immunization questions to a post-SIA survey ........................... 29 2.12. Designing for multiple outcomes ................................................................................................ 30 2.13. Designing for multiple geographic areas .................................................................................... 30 2.14. Designing for multiple levels of administrative or geographic hierarchy ................................... 31 ii 2.15. Reporting results by subgroups .................................................................................................. 33 3. Make concrete plans .................................................................................................................. 34 3.1. Set survey schedule .................................................................................................................... 34 3.2. Decide who will conduct the survey and create a project plan ................................................. 34 3.3. Obtain ethical clearance ............................................................................................................. 35 3.4. Design data collection tools and methods ................................................................................. 36 3.5. Choose data analysis tools .......................................................................................................... 40 3.6. Select a sample ........................................................................................................................... 40 3.7. Obtain access to health registers for vaccination records ......................................................... 48 3.8. Select and hire staff .................................................................................................................... 49 3.9. Train staff .................................................................................................................................... 54 4. Conduct field work ..................................................................................................................... 56 4.1. Collect data from households ..................................................................................................... 56 4.2. Check health registers from the health centre ........................................................................... 58 4.3. Monitor the quality of field data collection ................................................................................ 58 4.4. Check questionnaire forms and transmit ................................................................................... 60 4.5. Clusters that become suddenly inaccessible .............................................................................. 61 5. Data entry, cleaning and management ....................................................................................... 62 5.1. Database design .......................................................................................................................... 62 5.2. Data entry ................................................................................................................................... 62 5.3. Clean the dataset ........................................................................................................................ 63 5.4. Merge datasets and construct derived variables ....................................................................... 64 5.5. Generate a codebook ................................................................................................................. 66 6. Tabulation and analysis .............................................................................................................. 68 6.1. Conduct descriptive analyses to characterise the sample and assess its quality ....................... 69 iii 6.2. Calculate weights for analysis ..................................................................................................... 73 6.3. Conduct standard analyses ......................................................................................................... 73 6.4. Conduct additional analyses ....................................................................................................... 78 6.5. Classifying coverage .................................................................................................................... 86 7. Interpret, format, and share results ............................................................................................ 91 7.1. Draft the background section ..................................................................................................... 92 7.2. Draft the survey methods and limitations .................................................................................. 92 7.3. Draft the results section ............................................................................................................. 93 7.4. Draft the discussion section ........................................................................................................ 95 7.5. Develop implications and recommendations ............................................................................. 95 7.6. Revise the report and obtain clearance on final draft ................................................................ 98 7.7. Share the results ......................................................................................................................... 98 References ....................................................................................................................................... 101 iv List of boxes, figures and tables Boxes Box 1. Features of a good probability sample survey ................................................................................. 41 Box 2. Using Google Earth to segment large enumeration areas ............................................................... 46 Box 3. Essential components of a report .................................................................................................... 91 Figures Figure 1. Early steps in survey design ......................................................................................................... 10 Figure 2. Precise estimation uses larger sample sizes than classification .................................................. 16 Figure 3. The name “Organ Pipe Plots” is inspired by pipes like these ...................................................... 70 Figure 4. Organ pipe plots for four hypothetical strata, each with coverage of 50% ................................. 70 Figure 5. Organ