Using N-of-1 Methods to Explore Habit Formation

  • Dominika KwasnickaEmail author
  • Beatrice M. Konrad
  • Ian M. Kronish
  • Karina W. Davidson


Theories of the behaviour change and health behaviour change interventions are often tested in a conventional between-participant randomized controlled trial design; however, behaviour change interventions aim to achieve within-participant change in participants who are likely to have heterogeneous and unique responses to the behavioural intervention. Theories of behaviour change also apply to individuals. The aim of this chapter is to introduce the N-of-1 method (also known as single-participant N-of-1 trial) that employs a within-participant design to test predictors of behavioural outcomes and to deliver personalized behaviour change interventions that help people form and maintain healthy habits. We show how this design can be used to explore behaviour change and habit formation theory and inform future interventions. We conclude by describing how technological and statistical advances create new opportunities for researchers and practitioners of N-of-1 method to explore healthy habits at the individual level.


N-of-1 Single-case design Within-person design Personalized trials 


  1. Berkman, L. F., Blumenthal, J., Burg, M., Carney, R. M., Catellier, D., Cowan, M. J., et al. (2003). Effects of treating depression and low perceived social support on clinical events after myocardial infarction: The Enhancing Recovery in Coronary Heart Disease Patients (ENRICHD) Randomized Trial. Journal of the American Medical Association, 289(23), 3106–3116.CrossRefGoogle Scholar
  2. Burg, M. M., Schwartz, J. E., Kronish, I. M., Diaz, K. M., Alcantara, C., Duer-Hefele, J., et al. (2017). Does stress result in you exercising less? Or does exercising result in you being less stressed? Or is it both? Testing the bi-directional stress-exercise association at the group and person (N of 1) level. Annals of Behavioral Medicine, 51(6), 799–809.CrossRefGoogle Scholar
  3. Davidson, K. W., & Cheung, Y. K. (2017). Envisioning a future for precision health psychology: Innovative applied statistical approaches to N-of-1 studies. Health Psychology Review, 11(3), 292–294.CrossRefGoogle Scholar
  4. Duan, N., Kravitz, R. L., & Schmid, C. H. (2013). Single-patient (n-of-1) trials: A pragmatic clinical decision methodology for patient-centered comparative effectiveness research. Journal of Clinical Epidemiology, 66(Suppl. 8), S21–S28. Scholar
  5. Fernandez, Y. G. E., Nguyen, H., Duan, N., Gabler, N. B., & Kravitz, R. L. (2010). Assessing heterogeneity of treatment effects: Are authors misinterpreting their results? Health Services Research, 45(1), 283–301. Scholar
  6. Frasure-Smith, N., Lespérance, F., Gravel, G., Masson, A., Juneau, M., & Bourassa, M. (2002). Long-term survival differences among low-anxious, high-anxious and repressive copers enrolled in the Montreal heart attack readjustment trial. Psychosomatic Medicine, 64, 571–579.PubMedGoogle Scholar
  7. Gardner, B., Abraham, C., Lally, P., & de Bruijn, G.-J. (2012). Towards parsimony in habit measurement: Testing the convergent and predictive validity of an automaticity subscale of the Self-Report Habit Index. International Journal of Behavioral Nutrition and Physical Activity, 9(1), 102.CrossRefGoogle Scholar
  8. Guyatt, G., Sackett, D., Taylor, D., Chong, J., Roberts, R., & Pugsley, S. (1986). Determining optimal therapy—Randomized trials in individual patients. New England Journal of Medicine, 314, 889–892.CrossRefGoogle Scholar
  9. Hall, S. M., Tuskell, C. D., Vila, K. L., & Duffy, J. (1992). Weight gain prevention and smoking cessation: Cautionary findings. American Journal of Public Health, 82, 799–803.CrossRefGoogle Scholar
  10. Jakicic, J. M., Davis, K. K., Rogers, R. J., King, W. C., Marcus, M. D., Helsel, D., et al. (2016). Effect of wearable technology combined with a lifestyle intervention on long-term weight loss: The IDEA randomized clinical trial. JAMA, 316(11), 1161–1171. Scholar
  11. Johnston, D. W., & Johnston, M. (2013). Useful theories should apply to individuals. British Journal of Health Psychology, 18(3), 469–473.CrossRefGoogle Scholar
  12. Kravitz, R. L., Duan, N., Niedzinski, E. J., Hay, M. C., Subramanian, S. K., & Weisner, T. S. (2008). What ever happened to N-of-1 trials? Insiders’ perspectives and a look to the future. The Milbank Quarterly, 86(4), 533–555. Scholar
  13. Kwasnicka, D., Dombrowski, S. U., White, M., & Sniehotta, F. F. (2017). N-of-1 study of weight loss maintenance assessing predictors of physical activity, adherence to weight loss plan and weight change. Psychology & Health, 32(6), 686–708.CrossRefGoogle Scholar
  14. Lally, P., Van Jaarsveld, C. H., Potts, H. W., & Wardle, J. (2010). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, 40(6), 998–1009.CrossRefGoogle Scholar
  15. Lamiell, J. T. (1998). ‘Nomothetic’ and ‘Idiographic’: Contrasting Windelband’s understanding with contemporary usage. Theory & Psychology, 8(1), 23–38.CrossRefGoogle Scholar
  16. McDonald, S., Quinn, F., Vieira, R., O’Brien, N., White, M., Johnston, D. W., et al. (2017). The state of the art and future opportunities for using longitudinal n-of-1 methods in health behaviour research: A systematic literature overview. Health Psychology Review, 11(4), 307–323. Scholar
  17. Michie, S., & Johnston, M. (2012). Theories and techniques of behaviour change: Developing a cumulative science of behaviour change. Health Psychology Review, 6(1), 1–6. Scholar
  18. Mokdad, A. H., Marks, J. S., Stroup, D. F., & Gerberding, J. L. (2004). Actual causes of death in the United States, 2000. JAMA, 291(10), 1238–1245. Scholar
  19. Murad, M., Asi, N., Alsawas, M., & Alahdab, F. (2016). New evidence pyramid. Evidence Based Medicine, 21(4), 125.CrossRefGoogle Scholar
  20. Norman, G. J. (2008). Answering the “what works?” question in health behavior change. American Journal of Preventive Medicine, 34(5), 449–450.CrossRefGoogle Scholar
  21. Nyman, S. R., Goodwin, K., Kwasnicka, D., & Callaway, A. (2016). Increasing walking among older people: A test of behaviour change techniques using factorial randomised N-of-1 trials. Psychology & Health, 31(3), 313–330.CrossRefGoogle Scholar
  22. Ouellette, J. A., & Wood, W. (1998). Habit and intention in everyday life: The multiple processes by which past behavior predicts future behavior. Psychological Bulletin, 124(1), 54–74. Scholar
  23. Sackett, D. L., Sharon, E. S., & Richardson, W. S. (2000). Evidence-based medicine: How to practice and teach EBM (2nd ed.). London: Churchill Livingstone.Google Scholar
  24. Shiffman, S., Stone, A. A., & Hufford, M. R. (2008). Ecological momentary assessment. Annual Review of Clinical Psychology, 4, 1–32.CrossRefGoogle Scholar
  25. Spring, B., Ockene, J. K., Gidding, S. S., Mozaffarian, D., Moore, S., Rosal, M. C., et al. (2013). Better population health through behavior change in adults: A call to action. Circulation, 128(19), 2169–2176. Scholar
  26. Stroop, J. R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 643–662.CrossRefGoogle Scholar
  27. Verplanken, B., & Orbell, S. (2003). Reflections on past behavior: A self-report index of habit strength. Journal of Applied Social Psychology, 33(6), 1313–1330.CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Dominika Kwasnicka
    • 1
    Email author
  • Beatrice M. Konrad
    • 2
  • Ian M. Kronish
    • 2
  • Karina W. Davidson
    • 2
  1. 1.Faculty of Health SciencesSchool of Psychology, Curtin UniversityPerthAustralia
  2. 2.Center for Behavioral Cardiovascular HealthColumbia University Medical CenterNew YorkUSA

Personalised recommendations