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Looking at the PREPARE data or “How (not) to open Pandora’s box”

Looking at the PREPARE data or “How (not) to open Pandora’s box”. S.M. Eggers. So far, so good…. Gender at baseline and at follow-up. Next, age difference between T1 and T2. Next, have you ever had vaginal sex?. Also in Cape Town! Vaginal or anal or oral sex (combined)

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Looking at the PREPARE data or “How (not) to open Pandora’s box”

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  1. Looking at the PREPARE data or “How (not) to open Pandora’s box” S.M. Eggers

  2. So far, so good…

  3. Gender at baseline and at follow-up

  4. Next, age difference between T1 and T2

  5. Next, have you ever had vaginal sex?

  6. Also in Cape Town! Vaginal or anal or oral sex (combined) Condom use at last intercourse

  7. 211 instead of 1006 inconsistent answers

  8. Dar es Salaam: No of participants that scored inconsistently: 30.9% (1575) No of participants that had more than one inconsistency: 7.9% (401) No of participants that had more than two inconsistencies: 1.9% (96)

  9. Dar es Salaam: Are these inconsistencies randomly distributed? Self-efficacy to talk about sex (r = .15) Communicating with peers about sex (r = .19) No other variables CONCLUSIONS: The inconsistencies seem to be mainly caused by ‘mistakes’. Perhaps improving the instructions could help future surveys. We need to cross-validate these outcome variables before running analyses.

  10. Cape Town: No of participants that scored inconsistently: 49.7% (1762) No of participants that had more than one inconsistency: 21.6% (757) No of participants that had more than two inconsistencies: 9.6% (337)

  11. Cape Town: Are these inconsistencies randomly distributed? Being male (r = .15)* Being older (r = .23)* Lower SES (r = -.16) Less risk perception: perceived susceptibility (r = -.14) and severity (r = -.18) No other variables CONCLUSIONS: The inconsistencies seem to be mainly caused by ‘mistakes’. Perhaps improving the instructions could help future surveys. We need to cross-validate these outcome variables before running analyses.

  12. CONCLUSIONS: • Internal consistency & test-retest reliability: OK • Amount of inconsistencies: OK(-ish)?

  13. CONCLUSIONS: • Internal consistency & test-retest reliability: OK • Amount of inconsistencies: OK(-ish)? • Avoid reversed framing of questions? • Including reversely framed questions can also be useful

  14. CONCLUSIONS: • Internal consistency & test-retest reliability: OK • Amount of inconsistencies: OK(-ish)? • Avoid reversed framing of questions? • Including reversely framed questions can also be useful • Raw data entering is essential to trace these issues

  15. CONCLUSIONS: • Internal consistency & test-retest reliability: OK • Amount of inconsistencies: OK(-ish)? • Avoid reversed framing of questions? • Including reversely framed questions can also be useful • Raw data entering is essential to trace these issues • Tablets/PDA’s can be programmed to detect (and not to accept) invalid codes, inconsistent combinations and illogical time sequences

  16. CONCLUSIONS: • Internal consistency & test-retest reliability: OK • Amount of inconsistencies: OK(-ish)? • Avoid reversed framing of questions? • Including reversely framed questions can also be useful • Raw data entering is essential to trace these issues • Tablets/PDA’s can be programmed to detect (and not to accept) invalid codes, inconsistent combinations and illogical time sequences • Always try to cross-validate your variables before you trust your results ! ! !

  17. Big thanks to: • CT team: Cathy, Joy, Petra, Tracy • Dar team: Sylvia, Lusajo, Mrema, Elia • Limpopo team: Hans, Susan • Kampala team: Anne, Cecily

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