© 2006 IMS Health Incorporated or its affiliates. All rights reserved. June 20, 2007 Determination of Target Sample Sizes for Physicians Surveys Darrell J. Philpot Kennon R. Copeland IMS Health

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Outline Overview Physician Panel Survey Participation Selected Physician Survey Methodologies Non-participation Considerations Prior Participation Rate Modeling New Participation Rate Models Implications for Physician Sample Design Summary

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Overview Sample design is established based upon number of completed responses  Total size, allocation to strata developed to provide most efficient estimates Non-participation will reduce effective sample size  Sample variance will be greater than that targeted by design  If weighting carried out at higher level than design, can adversely affect accuracy of estimates Sample design should account for expected participation rates  Logistic modeling typically carried out  Olsen, et. al., looked at problem from Bayesian point of view

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Physician Panel Survey Participation Survey Recruitment  Noncontact: Unable to contact sample unit before end of survey recruitment period  Ineligible: Sample unit not in scope for survey  Non-agree: Sample unit is eligible, but refuses or is otherwise not available to report  Agree: Sample unit is eligible and agrees to participate Survey Reporting Nonreporter: Agreed sample unit does not return survey form Reporter: Agreed sample unit returns survey form Panel Survey Reporting  Reporting rates may differ for first, subsequent interview periods

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Physician Panel Survey Participation Components Noncontacts 1 st Period Reporters Non-agrees Nonreporters Selected Sample Subsequent Period Reporters Subsequent Period Nonreporters Agrees Ineligibles

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Physician Survey Methodology: National Disease and Therapeutic Index Office-based physicians, recording information on all patient contacts in assigned reporting period Panel of physicians 1,373 per month 4,120 unique per quarter Stratified by 108 primary specialties by 9 geographic divisions (sample design) Aggregated into 30 group specialties by 4 geographic regions (estimation) Reporting period 2 randomly selected, consecutive days per quarter

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Physician Survey Methodology: Office Promotion Report Office-based physicians, recording information on all pharmacy rep contacts in reporting period Panel of physicians 4,011 per month Stratified by 27 group specialties by 43 state groups (sample design) Aggregated into 27 group specialties by 4 regions (estimation) Reporting period Full month

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Physician Survey Methodology: Patient Contact Survey Office-based physicians, reporting information on patient contact days in reporting period Panel of physicians 4,011 per month Stratified by 30 group specialties by 4 regions (sample design) Aggregated into 30 group specialties by 4 regions (estimation) Reporting period Prior 5 days

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Participation Rate Modeling: Prior Models Historical models account for difference in response rate by: Specialty Group (collection of self defined primary specialty from either the AMA or AOA) Geography (State, Census Region)

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Participation Rate Modeling: New Models New models will include additional factors like: Age of physician Gender of physician Location (Urban/Rural, area economics) Type of practice Physician workload Resulting in increase accuracy in the predicted response rates

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Participation Rate Modeling (New): National Disease and Therapeutic Index

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Participation Rate Modeling (New): Office Promotion Reports

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Participation Rate Modeling (New): Patient Contact Survey

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Participation Rate Modeling: Implication for Sample Designs Sample Design become more complicated And/or post-stratification

© 2006 IMS Health Incorporated or its affiliates. All rights reserved. ICES III Physician Nonresponse June 20, Summary Factors other than Specialty and Geography can influence physicians willingness to participate in primary research study Impact can differs depending on the type of study Depending on the objective of the study it may be necessary to consider some of additional factors in your sampling plan to insure your desired number of respondents Age, gender, Type of practice, Urban/Rural setting, economics of the surround area or other