Akl et al., 2011 
Assess the effect of 1) tracking responses and 2) day of mailing (Monday vs Friday) on physician survey response rate
Directors of Family Medicine residency programs (ie GPs)
Training of residents in implementation of clinical guidelines
Two by two factorial randomized design
No tracking n = 228, Monday mailing n = 228
Tracking n = 228, Friday mailing n = 228
Asch et al., 1998 
To evaluate the effect of incentive size by providing physicians either a $5 bill or a $2 bill.
Primary care physicians identified from the American Medical Association Physician Master File
Attitudes about cost containment in cancer screening.
$2 cash incentive received in initial mailing n = 500
$5 cash incentive received in initial mailing n = 500
Baron et al., 2001 
To evaluate the cost effectiveness of a lottery on physicians response rates to a mail survey.
Family Doctors identified from membership list of the Quebec Federation of GPs
The determinants of influenza immunization among family physicians in Quebec.
No lottery n = 500
Lottery n = 500
Bonevskiet al., 2011 
To examine the efficacy of two strategies for improving general practitioner response to a survey and a secondary aim was to assess GPs self reported preferred mode of survey administration.
GPs practising in NSW selected from the Australasian Medical Publishing Company database.
The knowledge, attitudes and practices of GPs around vitamin D.
334 (Cover letter trial), 1166 (Telephone reminder trial)
Standard cover letter N = 167, No telephone reminder n = 576
Standard letter plus local division of general practice cover letter n = 167, Telephone reminder n = 590
Deehan et al., 1997 
To explore the effects of financial and non-financial inducements on response rates to increase the overall response rate.
A random sample of all GP’s in England and Wales.
Survey on GP’s work and attitudes with alcohol misusing patients.
Five arm parallel trial design with randomization
No inducement n = 1188
£5 charity donation n = 607, £10 charity donation n = 578, £5cash payment n = 613, £10 cash payment n = 598, (Total for all interventions n = 2396)
Drummond et al., 2008 
To investigate the effect of two low cost interventions (pre-contact and questionnaire order) on response to a primary care physician postal survey
Primary care physicians working in Ireland identified from various sources.
A national survey assessing views and practices of physicians regarding prostate specific antigen (PSA) testing.
Two by two factorial randomized design
No pre-contact n = 743, Version 2 survey (Topic specific questions first) n = 744
Pre-contact n = 715, Version 1 survey (general questions first) n = 714
Everett et al., 1997 
To examine the effectiveness of $1 incentive on response rates
Firearm-safety counseling beliefs
No incentive n=300
$1 bill n=300
Gattellari et al., 2012 
Assess effectiveness of two response-aiding strategies in a postal survey
GPs known to be in current practice
Management of nonvalvular atrial fibrillation
Two by two factorial randomized control trial
Mail prompt n = 500, Coloured seal without text n = 500
Fax prompt n = 500, Coloured seal + text n = 500
Gupta et al., 1997 
To determine the effectiveness of a telephone prompt by a medical researcher compared to a nonmedical research assistant in improving survey response rate of GP’s, and to compare personnel costs.
A national random sample of Australian GPs
A national survey assessing GPs views of clinical practice guidelines
Telephone prompt by a medical researcher n = 202
Telephone prompt by experienced nonmedical research assistant n = 202
Hocking et al., 2006 
To compare GP response to a telephone interview with response to a postal survey with three reminders.
A random sample of Victorian GPs
Survey to assess knowledge and diagnostic and management practices of genital chlamydia infection.
Postal survey n = 451
Telephone interview n = 416
James et al., 2011 
To study the effects of payment timing, form of payment and requiring a social security number (SSN) on survey response rates.
Practising US physicians ages 65 and under representing all specialties (including primary care), selected from the AMA Physician Masterfile
Survey on ethical and moral beliefs.
Four arm parallel design with randomization
Promised $US25 check requiring SSN n = 102
Immediate $US25 cash n = 129, Immediate $US25 check n = 97, Promised $US25 check not requiring SSN n = 115
McLaren and Shelley 2000 
To compare effect of a primer telephone call and postcard on GP response rate; and to compare the effect of informing GPs about a prize for participating in survey compared to not informing GPs of the prize.
Management issues surrounding early pregnancy bleeding and miscarriage
Two by two factorial design with randomization
Telephone n=305 No prize notification N=310
Postcard n=316Prize notification n=311
Maheux et al., 1989 
To determine the response rates of Quebec physicians by sending a handwritten thank you letter and by sending a more personalized mailout package.
To determine the level of physicians support for a number of patient care issues.
Second mailing N = 356, Third mailing N = 253
No handwritten postscript n = 186, Non-personalised mailout n = 127
Handwritten postscript n = 170, Personalised mailout n = 126
Olivarius and Andreasen, 1995 
To test a possible day the week effect on doctors response rate to a postal questionnaire.
A nationwide survey on doctors’ attitude on the relative importance of general practice and the specialties in the treatment of general diseases and diseases commonly regarded as belonging to the specialties.
Dispatch of survey on Thursday (for receipt before weekend) n = 98
Dispatch of survey on Saturday (for receipt after weekend) n = 102
Pedrana et al., 2008 
To compare response rates to postal surveys sent by normal post and registered mail and to assess the cost implications of the two mailing methods.
General practitioners in Victoria.
To assess antenatal screening practices in Australia
Normal mail n = 775
Registered mail n = 775
Pirotta et al., 1999 
To measure the effect of a primer postcard to improve mailed survey response rates.
Victorian GPs who had at least 1500 consultations in 1995-96
General Practitioners attitudes to complementary therapies.
No primer postcard n = 400
Primer postcard n = 400
Pit et al., 2013 
To assess the effectiveness of small non-conditional non-financial incentive (ie attractive pen) on survey response rates
Practicing GPs in Northern Rivers region of NSW
How to improve sustainable employment of ageing GPs in rural Australia
No pen incentive n = 62
Pen incentive n = 63
Robertson et al., 2005 
To test the effect of a $AUD2 scratch lottery ticket on response rates
A random sample GP’s and specialists from the medical directory of Australia.
To explore the uptake of 19 new drugs into the clinical practices of Australian GPs and specialists.
No lottery n = 232
AUD$2 scratch lottery n = 232
Scott et al., 2011
To compare effects and costs of three different modes of survey administration in a national survey of Doctors
A stratified random sample of doctors undertaking clinical practice from a national directory of all doctors in Australia. Stratification was by doctor type and rural/remote category.
Study of the dynamics of the medical labour market in Australia, focusing on workforce participation and its determinants among Australian doctors.
3-arm parallel trial design with randomisation
Online survey, followed by reminder letter with login details n = 369
Sequential mixed mode -online survey, followed by reminder letter with paper survey n = 388, Simultaneous mixed mode -paper survey and login details sent together, with reminder letter with login details n = 334
Seguin et al., 2004 
To compare email with regular mail for conducting surveys of family physicians.
A random sample of physicians listed in the college of family physicians of Canada’s database who had an email address
Survey on use of sildenafil citrate (Viagra)
Survey delivered by post to the physicians without email n = 800
Survey delivered by email n = 798, Survey delivered by post to the physicians with e mail n = 799
Shosteck and Fairweather, 1979 
Comparison of mail and personal administration of questionnaire among physicians.
Office-based primary care physicians who were in active practice within the States of Washington DC and Maryland, and treating upper respiratory or lower urinary tract infections selected from the AMA database.
Physician antibiotic prescription practices.
Mail technique n = 296
Personal interview technique n = 247
Thomson et al., 2004 
To maximise the response to a postal questionnaire and to test the most effective form of incentive.
Practicing GP’s selected from the Lothian Primary Care NHS Trust database.
GP’s attitudes to the management of ingrowing toenails.
Lottery of one chance to win six bottles of champagne n = 286
Lottery of six chances to win one bottle of champagne n = 282
Ward et al., 1998 
To evaluate response aiding strategies feasible in large surveys
Randomly selected sample of general practitioners
4-arm parallel trial design with randomisation
Doctor advance phone prompt: n = 249, Pen prompt: n = 261, Letter prompt: n = 260, Non-doctor advance phone prompt: n = 501