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No use reasoning with adolescents? A randomised controlled trial comparing persuasive messages


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A slideshow adapted from what I presented in the annual conference of the European Health Psychology Society. Features a persuasive communication experiment in the context of health behavior measurement.

Published in: Health & Medicine
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No use reasoning with adolescents? A randomised controlled trial comparing persuasive messages

  1. 1. Twitter: @heinonmatti Facebook: Heinon Matti SMS reminders to increase accelerometer wear-time A within-trial RCT comparing persuasive messages Reg. no: DRKS00007721 4.5.2016 1
  2. 2. Twitter: @heinonmatti Facebook: Heinon Matti Background 4.5.2016 2
  3. 3. Twitter: @heinonmatti Facebook: Heinon • Physical activity recommendations based on self- reported activity levels → problems: • Remembering past activity • Reporting “what the researcher wants to hear” • Solution: objective measurement devices • New problem: need to wear it for most of the study period! ‒ E.g. if you only wear the activity device when exercising, looks like 100% of your day was spent working out! 4.5.2016 3 The ”why”
  4. 4. Twitter: @heinonmatti Facebook: Heinon The ”why” • Let’s Move It ‒ A school-based multilevel intervention to increase physical activity and decrease sitting among youth* ‒ Ongoing since 2012 ‒ RCT phase from 2015 to 2017 ‒ Ca. 16–19 year-old vocational school students ‒ Waist-worn accelerometers used *Hankonen, Heino et al. (in preparation). Randomised controlled feasibility study of a school-based multi-level intervention to increase physical activity and decrease sedentary behaviour among older adolescents.
  5. 5. Twitter: @heinonmatti Facebook: Heinon The Pervasive Problem: non-wear in accelerometry • Let’s Move It Feasibility study • Students fell short of accelerometer wear targets (>10hrs of data on >4 days) ‒ Qualitative work: non-wear attributed to forgetting How do we ensure adequate accelerometer wear times?
  6. 6. Twitter: @heinonmatti Facebook: Heinon Matti Methods 4.5.2016 6
  7. 7. Twitter: @heinonmatti Facebook: Heinon The setup • Within-trial RCT during internal pilot study of the main trial • Participants wear the accelerometer for seven consecutive days during Let’s Move It baseline data collection • Fight forgetting with (SMS) reminders • Next question: What kind of reminders? Could an old copy machine help here?
  8. 8. Twitter: @heinonmatti Facebook: Heinon Langer, Blank and Chanowitz (1978) Mixed success w/ replication: Folkes (1987); Key, Edlund, Sagarin and Bizer (2009) ”Harnessing the power of ’Because’”…?
  9. 9. Twitter: @heinonmatti Facebook: Heinon Message types: an example ”Reason”, day 3:”Succinct”, day 3: “Hello! Because the study wouldn't succeed without your help, please remember to put on the motion measurement device again and wear it until you go to sleep (except in the shower etc.) - thanks!” [emphasis added] “Hello! Please remember to put on the motion measurement device again and wear it until you go to sleep (except in the shower etc.) - thanks!”
  10. 10. Twitter: @heinonmatti Facebook: Heinon Consenting in Let’s Move It accelerometry N=375 Opting in SMS n=276 Randomised to ”Reason” n=138 Randomised to ”Succinct” n=135 Send failed n=7 Opting out n=95 Participants:
  11. 11. Twitter: @heinonmatti Facebook: Heinon • Does providing a reason via SMS influence accelerometer wear time: ‒ Total wear time ‒ Number of days >10 hours of data accumulated (0-7) 4.5.2016 11 Research questions
  12. 12. Twitter: @heinonmatti Facebook: Heinon • ”Probability of observed (or rarer) data, if null hypothesis is true” • (also assumes randomisation, stopping rules etc…) 4.5.2016 12 What’s a ”p-value” again? When p is high (eg. p=0.32), no conclusions can be drawn! (Dienes, 2014) Reactions upon discovering this can vary.
  13. 13. Twitter: @heinonmatti Facebook: Heinon • remember, p-value: Probability of data, given H0 • A Bayes factor BF01: Pr(𝑑𝑎𝑡𝑎 𝑔𝑖𝑣𝑒𝑛 𝐻0) Pr(𝑑𝑎𝑡𝑎 𝑔𝑖𝑣𝑒𝑛 𝐻1) 4.5.2016 13 A better question? ”Which is more probable, null or alternative? 0 …∞1 31/3 Very roughly: BF01: Data favor alternative Insufficient data Data favor null A great explanation: When 1 10 < BF < 10, evidence quite weak
  14. 14. Twitter: @heinonmatti Facebook: Heinon Matti Results 4.5.2016 14
  15. 15. Twitter: @heinonmatti Facebook: Heinon Total wear time
  16. 16. Twitter: @heinonmatti Facebook: Heinon 4.5.2016 16 Total weartime differences Bayesian ANOVA gives us BF01=29.03 1:1 (50%) prior odds become 1:29, p(effect)=3% 10:1 (91%) prior odds become 10:29, p(effect)=26%
  17. 17. Twitter: @heinonmatti Facebook: Heinon Valid wear day percentages Χ2(7) = 7.893, p = 0.342 BF01 = 1.27BF01 = 7.09
  18. 18. Twitter: @heinonmatti Facebook: Heinon 4.5.2016 18 Measurement days of >10 hours of valid data Horizontal lines represent means, with shaded 95% Bayesian Highest Density Intervals (HDIs)
  19. 19. Twitter: @heinonmatti Facebook: Heinon Matti Discussion 4.5.2016 19
  20. 20. Twitter: @heinonmatti Facebook: Heinon Conclusions • Why didn’t reasons help? • Hidden moderators blah blah? • SMS format hinders the effect? (Why?) • Wearing the device a question of capability, not motivation? • No use reasoning with adolescents? ‒ E.g. university students more compliant • A case of an undead theory? ‒ Ferguson, C. J., & Heene, M. (2012). A Vast Graveyard of Undead Theories.
  21. 21. Twitter: @heinonmatti Facebook: Heinon Conclusions • Why didn’t reminders help? • Operationalisation failure? ‒ Messages claimed to have been read but no objective log data • Self selection? ‒ Unlikely, as opting in was mostly determined by recruitment prompt • Non-wear not due to remembering? ‒ Although they said it was and thought the reminder helped immensely!
  22. 22. Twitter: @heinonmatti Facebook: Heinon 4.5.2016 22 The Lakatos principle: Meehl, P. E. (1990). Appraising and amending theories: The strategy of Lakatosian defense and two principles that warrant it. Psychological Inquiry, 1(2), 108–141. “Accepting the neo-Popperian view that it is inadvisable to persist in defending a theory against apparent falsifications […] the rationale for defending by non-ad hoc adjustments lies in the theory having accumulated credit by strong successes, having lots of money in the bank.“ – Paul Meehl - Does the “power of because” lean on Monopoly money?
  23. 23. Twitter: @heinonmatti Facebook: Heinon Thank you! @heinonmatti Questions? Comments? Ideas?