title: Using the Web to Collect Data on Sensitive Behaviours: A Study Looking at Mode Effects on the British National Survey of Sexual Attitudes and Lifestyles.
abstract: BACKGROUND
  Interviewer-administered surveys are an important method of collecting population-level epidemiological data, but suffer from declining response rates and increasing costs. Web surveys offer more rapid data collection and lower costs. There are concerns, however, about data quality from web surveys. Previous research has largely focused on selection biases, and few have explored measurement differences. This paper aims to assess the extent to which mode affects the responses given by the same respondents at two points in time, providing information on potential measurement error if web surveys are used in the future.
  
  
  METHODS
  527 participants from the third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3), which uses computer assisted personal interview (CAPI) and self-interview (CASI) modes, subsequently responded to identically-worded questions in a web survey. McNemar tests assessed whether within-person differences in responses were at random or indicated a mode effect, i.e. higher reporting of more sensitive responses in one mode. An analysis of pooled responses by generalized estimating equations addressed the impact of gender and question type on change.
  
  
  RESULTS
  Only 10% of responses changed between surveys. However mode effects were found for about a third of variables, with higher reporting of sensitive responses more commonly found on the web compared with Natsal-3.
  
  
  CONCLUSIONS
  The web appears a promising mode for surveys of sensitive behaviours, most likely as part of a mixed-mode design. Our findings suggest that mode effects may vary by question type and content, and by the particular mix of modes used. Mixed-mode surveys need careful development to understand mode effects and how to account for them.
authors: Research Department of Infection and Population Health, University College London, London, United Kingdom.|Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
authors: Sarah
authors: S
authors: Burkill
authors: Research Department of Infection and Population Health, University College London, London, United Kingdom.
authors: Andrew
authors: A
authors: Copas
authors: Institute for Social Research, University of Michigan, Ann Arbor, United States of America.
authors: Mick P
authors: MP
authors: Couper
authors: Research Department of Infection and Population Health, University College London, London, United Kingdom.
authors: Soazig
authors: S
authors: Clifton
authors: Research Department of Infection and Population Health, University College London, London, United Kingdom.
authors: Philip
authors: P
authors: Prah
authors: Department of Social and Environmental Research, London School of Hygiene and Tropical Medicine, London, England.
authors: Jessica
authors: J
authors: Datta
authors: Institute for Social Research, University of Michigan, Ann Arbor, United States of America.
authors: Frederick
authors: F
authors: Conrad
authors: Department of Social and Environmental Research, London School of Hygiene and Tropical Medicine, London, England.
authors: Kaye
authors: K
authors: Wellings
authors: Research Department of Infection and Population Health, University College London, London, United Kingdom.
authors: Anne M
authors: AM
authors: Johnson
authors: Research Department of Infection and Population Health, University College London, London, United Kingdom.|Department of Health Services Research & Policy, London School of Hygiene and Tropical Medicine, London, England.
authors: Bob
authors: B
authors: Erens
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001290:Attitude; D003625:Data Collection / Q000379:methods*; D005260:Female; D006306:Health Surveys; D006801:Humans; D020407:Internet; D008019:Life Style; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D012725:Sexual Behavior; D012923:Social Class; D011795:Surveys and Questionnaires; D006113:United Kingdom; D055815:Young Adult