Table 3

Validity and reactivity findings for studies using web-based diaries

 Garry et al32
  • Compared daily diaries with surprise retrospective survey 6–12 months later

  • Under-reported number of partners (p=0.02) on survey

  • Over-reported frequency of any sex, vaginal sex and oral sex on survey (all p<0.01)

  • Over-reported condom use for vaginal (p=0.02) and oral sex (p=0.06) on survey

  • Vaginal sex was reported four times more often in retrospective survey than diaries

  • No significant differences in recall of anal sex

  • Participants could not accurately predict their recall accuracy on retrospective survey

 Glick et al33
  • Compared twice weekly, weekly and biweekly diaries with 3 month retrospective survey

  • Non-significant under-reporting on retrospective survey

  • Most concordance correlation coefficient and κ statistics ≥80%

 Horvath et al37
  • Compared daily diary with retrospective survey

  • Over-reported receptive oral and anal sex on survey (all p<0.05)

  • Greater frequency of giving oral sex (p<0.05), receiving oral sex (p<0.01), and higher number of sexual events (p<0.01) were associated with over-reporting on survey

  • Greater frequency of unprotected insertive anal sex was associated with under-reporting on survey (p<0.001)

  • 28–85% of participants over-reported or under-reported each behaviour on the retrospective survey

 Lim et al2
  • Compared online, text-message and paper weekly diaries with retrospective survey

  • Correlation was high for proportion of partners considered ‘regular’ (0.87), frequency of sex (0.76), frequency of condom use (0.76) and STI risk (0.74)

  • Correlation was lower for number of partners (0.63) and proportion of partners considered ‘new’ (0.57)

 Glick et al33
  • Compared recall from active diary participants with controls

  • Controls had 0.9 more new male partners than diary subjects (p=0.05)

  • Controls had significantly greater increases in frequency of anal sex (p=0.01), frequency of unprotected anal sex (p<0.01) and any unprotected anal sex (p<0.01)

  • Controls had significantly higher STI and HIV diagnosis incidence rates (26.1%) than active diary participants (4.8%, p=0.01)

  • No evidence of dose-response by diary frequency

  • Author explanation: difference in HIV/STI incidence indicates that risky behaviour may have actually differed over time between groups; attributed to diaries because of controlled nature of study

 Hensel et al3
  • Diary completion fell significantly over time (-0.61%/week, p<0.05)

  • Reports of vaginal sex decreased significantly over time (−0.61%/week, p<0.05)

  • Greater decrease in vaginal sex was reported in 18–20-year-olds (−0.91%/week), 27–29 year-olds (−0.83%/week), men (−0.80%/week) and patients without STI at enrolment (−0.68%/week) (all p<0.05)

  • Author explanation: slight differences in reported behaviour during study may be due to subtle changes in behaviour over time, not diary participation

 Horvath et al37
  • Statistically significant decline in giving oral sex, receiving oral sex, insertive anal sex and unprotected receptive anal sex over time (all p<0.05)

  • Author explanation: diary completion leads to self-monitoring, which causes participants to reduce risky behaviours over time

 Kiene et al, Kiene et al38 39
  • No evidence of reactivity

 Newcomb, Newcomb and Mustanski43 44
  • No evidence of reactivity

  • *Over-reporting and under-reporting on retrospective surveys compared with diaries.