June 20, 2007© 2006 IMS Health Incorporated or its affiliates. All rights reserved.

Determination of Target Sample Sizes for Physicians Surveys

Darrell J. PhilpotKennon R. Copeland

IMS Health

ICES III Physician Nonresponse • June 20, 20072 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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

ICES III Physician Nonresponse • June 20, 20073 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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

ICES III Physician Nonresponse • June 20, 20074 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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

ICES III Physician Nonresponse • June 20, 20075 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

Physician Panel Survey Participation Components

Noncontacts

1st Period Reporters

Non-agrees

Nonreporters

Selected Sample

Subsequent Period

Reporters

Subsequent Period

Nonreporters

AgreesIneligibles

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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

ICES III Physician Nonresponse • June 20, 20077 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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

ICES III Physician Nonresponse • June 20, 20078 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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

ICES III Physician Nonresponse • June 20, 20079 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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)

Central East South WestALR 44% 66% 56% 55%AOS 69% 73% 71% 64%CD 68% 64% 68% 57%CRS 66% 78% 77% 76%DO 39% 39% 34% 33%DRM 60% 79% 65% 72%EM 23% 19% 26% 23%END 46% 44% 51% 41%FP 58% 54% 68% 65%FPP 71% 64% 70% 64%GE 50% 56% 71% 61%GER 41% 44% 55% 59%GP 64% 66% 74% 75%GPP 61% 64% 76% 64%GS 60% 59% 59% 53%HEM 72% 71% 69% 70%IM 49% 49% 54% 41%NEP 60% 54% 63% 54%NEU 72% 59% 47% 58%OBG 67% 72% 70% 61%ONC 61% 67% 64% 62%

Participation Rate by Specialty and RegionRegionSpecialty

Group

GeoSpecpit 210)(log

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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

kkXGenderGeoSpecpit ........)(log 3210

Female Male20 - 39 33% 35%40 - 49 50% 56%50 - 59 60% 68%60 - 69 59% 67%70+ 61% 58%

GenderParticipation Rate

Age Group

ICES III Physician Nonresponse • June 20, 200711 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

Participation Rate Modeling (New):National Disease and Therapeutic Index

F M F M F M F MALR 84% 82% 81% 76% 78% 73% 80% 78%AOS 77% 86% 75% 86% 90% 72% 20% 84%CD 90% 78% 93% 79% 57% 69% 91% 65%CRS 69% 77% 92% 77% 89% 79% 40% 17%DO 73% 76% 74% 80% 35% 81% 72% 74%DRM 76% 83% 74% 79% 62% 83% 70% 80%EM 60% 79% 67% 65% 56% 67% 42% 75%END 64% 71% 85% 88% 73% 69% 80% 73%FP 63% 80% 63% 75% 71% 78% 83% 79%FPP 67% 66% 86% 83% 81% 79% 80% 74%GE 67% 85% 67% 78% 67% 85% 75% 87%GER 66% 68% 50% 88% 68% 73% 44% 68%GP 73% 92% 79% 75% 83% 80% 93% 87%GPP 94% 78% 92% 79% 67% 92% 68% 66%GS 60% 78% 50% 91% 92% 82% 90% 83%HEM 64% 85% 60% 63% 96% 84% 89% 69%IM 59% 72% 76% 79% 73% 75% 73% 78%NEP 57% 65% 70% 67% 60% 66% 96% 83%NEU 86% 68% 68% 83% 68% 72% 64% 74%OBG 80% 80% 67% 75% 64% 71% 53% 79%ONC 76% 74% 77% 83% 86% 76% 58% 73%OPH 84% 80% 85% 89% 81% 80% 40% 87%ORS 13% 66% 50% 80% 96% 79% 50% 88%

Specialty Group

Region and GenderCentral East South West

ICES III Physician Nonresponse • June 20, 200712 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

Participation Rate Modeling (New):Office Promotion Reports

F M F M F M F MALR 94% 88% 82% 84% 93% 82% 47% 92%ANE 83% 94% 70% 91% 88% 90% 92% 90%AOS 90% 89% 17% 88% 82% 89% 70% 79%CD 89% 81% 92% 84% 89% 76% 95% 77%CRS 95% 81% 90% 79% 92% 84% 50% 72%DO 65% 80% 70% 74% 73% 74% 84% 79%DRM 92% 79% 82% 85% 79% 81% 88% 86%END 75% 85% 96% 86% 87% 77% 93% 70%FP 77% 83% 78% 80% 75% 77% 80% 86%FPP 74% 74% 88% 88% 88% 80% 86% 79%GE 90% 82% 59% 77% 68% 70% 93% 87%GP 89% 96% 95% 94% 87% 86% 97% 88%GPP 79% 86% 93% 88% 96% 90% 92% 88%GS 96% 93% 83% 84% 62% 82% 93% 89%IM 75% 78% 84% 86% 78% 79% 74% 79%NEP 89% 88% 33% 75% 51% 83% 56% 72%NEU 78% 75% 53% 83% 80% 74% 89% 81%OBG 67% 78% 85% 83% 71% 78% 62% 80%ONC 88% 79% 81% 83% 84% 83% 81% 80%OPH 83% 93% 46% 90% 82% 83% 73% 80%ORS 72% 77% 55% 78% 58% 82% 94% 78%OTO 90% 78% 70% 89% 36% 82% 30% 82%PED 84% 81% 85% 88% 73% 82% 80% 86%PSY 64% 81% 82% 85% 79% 86% 82% 87%PUD 45% 95% 90% 86% 33% 84% 70% 71%RHU 93% 93% 83% 94% 92% 95% 98% 94%URL 73% 89% 80% 82% 80% 77% 65% 85%

Specialty Group

Region and GenderCentral East South West

ICES III Physician Nonresponse • June 20, 200713 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

Participation Rate Modeling (New):Patient Contact Survey

F M F M F M F MALR 38% 46% 67% 66% 52% 58% 34% 61%AOS 43% 71% 50% 75% 50% 73% 58% 64%CD 63% 68% 47% 67% 60% 68% 32% 60%CRS 50% 68% 58% 80% 69% 78% 75% 76%DO 30% 42% 25% 44% 24% 38% 23% 36%DRM 57% 62% 75% 83% 62% 68% 70% 74%EM 20% 24% 17% 20% 24% 27% 19% 23%END 36% 52% 39% 48% 44% 54% 36% 44%FP 48% 64% 47% 59% 60% 71% 61% 67%FPP 60% 72% 56% 66% 70% 69% 50% 67%GE 53% 50% 42% 58% 76% 70% 47% 64%GER 48% 38% 38% 52% 48% 61% 55% 63%GP 44% 67% 63% 67% 63% 76% 76% 75%GPP 59% 62% 62% 64% 74% 76% 68% 63%GS 48% 62% 53% 60% 48% 60% 46% 54%HEM 58% 78% 69% 72% 55% 73% 47% 79%IM 45% 51% 38% 56% 41% 60% 30% 48%NEP 47% 63% 44% 56% 42% 66% 38% 59%NEU 62% 74% 45% 62% 35% 49% 52% 60%OBG 64% 69% 68% 75% 62% 75% 55% 66%ONC 49% 67% 60% 71% 44% 71% 56% 64%OPH 63% 83% 66% 82% 81% 79% 67% 79%ORS 86% 73% 67% 75% 44% 62% 31% 50%OTO 57% 61% 60% 60% 56% 65% 60% 63%PED 59% 68% 59% 72% 57% 64% 54% 60%

Region Gender

Specialty Group

Central East South West

ICES III Physician Nonresponse • June 20, 200714 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

Participation Rate Modeling:Implication for Sample Designs

Sample Design become more complicatedAnd/or post-stratification

ICES III Physician Nonresponse • June 20, 200715 © 2006 IMS Health Incorporated or its affiliates. All rights reserved.

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