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  • A contingency management smoking cessation intervention (2017 -2018)

    Date: 2017 - 2018

    Research team: Harold Kincaid, Andre Hofmeyr and Olivia Rusch (Masters)

    Tobacco consumption is a pressing global issue, leading to approximately six million deaths each year. In South Africa, the smoking prevalence rate is stubbornly high, implying that a successful smoking cessation programme could have large social benefits, particularly if it targets young smokers. Contingency management (CM) interventions, which provide cash transfers conditional on biochemically-verified abstinence, have been effective in bringing about increased smoking cessation rates. However, the cost, complexity, and staff burden of CM interventions act as a barrier to their widespread adoption. For example, CM requires frequent monitoring of participants; tracking of participants’ substance use and reinforcement history; and, often significant, funds to pay for abstinence incentives.

    As a response to this issue, we conduct a randomised controlled trial (RCT) to test whether a low-cost, low-intensity CM intervention is an effective form of treatment for tobacco addiction in a student population. The programme provides relatively modest abstinence-contingent cash rewards and had a low staff burden. The decision to target students was based on a number of factors: they are easy to recruit and track; their lifetime exposure to cigarettes and their smoking intensity tend to be low compared to older smokers so they may be more susceptible to an intervention (Mayhew et al. 2000); their relatively low incomes mean that the rewards on offer may be more salient to them than people in fulltime employment; and, if the programme is successful at getting them to quit smoking, the personal and societal benefits are large and continue to accrue over time.

    In addition, our study goes beyond previous research that focusses on the efficacy of CM as a tool for treating tobacco addiction. Previous studies have taken an epidemiological approach to the impact of cessation programmes on smoking prevalence and intensity. In addition to taking measures of smoking outcomes, we use sophisticated techniques to elicit and estimate the risk preferences and time preferences of smokers involved in our cessation programme. The combination of these sources of information allow us to investigate whether a relationship exists between a smoker’s risk and time preferences and their participation and success in the cessation programme. This has clear policy relevance. For example, if people who are less risk averse and/or who discount the future at a higher rate are less likely to succeed in the programme, it may be necessary to adapt the CM design to target these ‘hard-to-treat’ smokers (e.g. front-loading the incentive schedule by offering larger rewards at the start of the cessation programme).

    In sum, we investigate the efficacy of a low-cost, low-intensity CM smoking cessation intervention in a sample of university students and analyse the behavioural correlates of the decision to quit and the likelihood of remaining abstinent.

  • Washing with hope: inducing hand washing habit formation amongst children (2015 -2017)

    Date: 2014 - 2018

    Research team: Justine Burns, Brendan Maughan-Brown, Abigail Sellman (Masters) and Aurea Mouzinho

    Handwashing with soap at critical times is a simple and effective way to prevent the spread of communicable diseases, such as diarrhoea and acute respiratory infection, which are major causes of morbidity and mortality in the developing world.  However, rates of handwashing remain low, and interventions which attempt to improve handwashing behaviours have largely been unsuccessful in practice.

    In 2014, we conducted a pilot randomised evaluation in a poor urban community in Cape Town to measure the impacts of HOPE SOAP© – a translucent bar of soap with a toy inside of it, designed to make handwashing fun for children.  In the pilot, 229 households were randomly assigned to receive four deliveries of HOPE SOAP© over a period of eight weeks. 

    At endline, HOPE SOAP© children were directly observed as being more likely to wash their hands unprompted prior to eating a snack; were more likely to use soap when washing their hands; had better health outcomes on average; and those who used the soap as intended, and did not cheat to remove the toy from the soap, were less likely to have been ill. We also find evidence of positive intra-household spillover effects.  Evidence suggests that a child’s assignment to HOPE SOAP© had a positive impact on the handwashing behaviour of their caregiver. Investigation of the causal mechanisms for this effect suggests that HOPE SOAP© affected caregiver behaviour both by disrupting existing poor-hygiene habits, and strengthening handwashing norms within households.

    Because of the encouraging results of the 2014 pilot, we plan to scale up the study to a fully-powered randomised controlled trial in Sierra Leone. We expect the study to commence in early 2019 and are currently conducting exploratory fieldwork finalising our research protocols and developing competitive funding applications.


    • Burns, J., Maughan-Brown, B., Mouzinho, A. (2017). Washing with Hope: Evidence from a hand-washing pilot study among children in South Africa. A Southern Africa Labour and Development Research Unit Working Paper Number 199. Cape Town: SALDRU, University of Cape Town
    • Sellman, A., Burns, J., Maughan-Brown, B., (2018). Handwashing behaviour and habit formation in the household: evidence of spillovers from a pilot randomised evaluation in South Africa. A Southern Africa Labour and Development Research Unit Working Paper. Cape Town: SALDRU, University of Cape Town.
    • Burns J, Maughan-Brown B, Âurea Mouzinho. Washing with Hope: Evidence of improved handwashing among chi
  • Understanding addiction: using economic experiments to understand the dynamics of tobacco smoking (2015 - 2017)

    Date: 2015 - 2017

    Research team: Harold Kincaid, Andre Hofmeyr, Don Ross and Glenn Harrison

    Addiction is a pressing social problem internationally and especially in South Africa. It is important that the best tools of economics be applied to addictive behaviour to aid in the successful development of policy and interventions. This project seeks to advance that goal.

    Addiction is an important problem for economic theory: why do most addicts expend resources to acquire their targets of addiction but then incur real costs to try and reduce or limit their consumption of these goods? Furthermore, why is the typical course of addiction characterised by repeated unsuccessful attempts to quit prior to final abstention? From the standpoint of standard consumer theory in economics these patterns of behaviour are difficult to rationalise. There is a theoretical literature in economics which models habit-forming behaviours, of which addiction is an extreme type, but there is a paucity of experimental economic studies eliciting and comparing the preferences – specifically, instantaneous risk preferences, time preferences, and intertemporal risk preferences – and beliefs that economic theory suggests may differ between addicts and non-addicts. The experimental research that has been conducted has been dominated by psychologists, and some economists have begun to follow their methodological lead. However, detailed reviews of the experimental literature on addiction highlight a number of methodological and statistical limitations in the ways these data have been collected and analysed.

    We elicited the instantaneous risk preferences, time preferences, intertemporal risk preferences, and subjective beliefs of student and staff samples of smokers and non-smokers at the University of Cape Town using an incentive-compatible experimental design. We will use a cutting-edge maximum likelihood statistical framework, which is consistent with the data generating processes proposed by structural theories and accounts for subject errors in decision making, to draw robust inferences about the relationship between instantaneous risk preferences, time preferences, intertemporal risk preferences, subjective beliefs and addiction. The end product will be a better understanding of addiction to inform policy and interventions to treat addictive behaviours.

  • The behavioural identification and prevalence of pathological gamblers in Denmark (2015)

    Date: 2015

    Research team: Glenn Harrison, Morten Lau, Don Ross and J. Todd Swarthout

    We first designed and conducted a survey to estimate the prevalence of disordered gambling among Danish adults. We then randomly selected a subset of respondents, weighted so as to over-sample those with high disordered gambling risk scores, and conducted a series of experiments with them. These included experiments designed to elicit risk preferences, and experiments in which subjects gambled online on simulated slot machines we designed. All experiments were also conducted, for purposes of control and calibration, on a sample of Georgia State University undergraduates.


    • Harrison, G., Lau, M., Ross, D., & Swarthout, J.T., Small stakes risk aversion in the laboratory: A reconsideration. Economics Letters 160: 24-28, 2017.
    • Harrison, G., Jessen, L., Lau, M. & Ross, D. 2018. Disordered gambling prevalence: Methodological innovations in a general Danish population survey. Journal of Gambling Studies, 34(1): 225-253.


  • Harrison, G., Jessen, L., Lau, M., & Ross, D. 2018. Disordered gambling prevalence: Methodological innovations in a general Danish population survey. Journal of Gambling Studies, 34(1): 225-253.https://doi.org/10.1007%2Fs10899-017-9707-1
  • Hofmeyr, A., Monterosso, J., Dean, A.C., Morales, A.M., Bilder, R.M., Sabb, F.W., & London, E.D. 2017. Mixture models of delay discounting and smoking behaviour. The American Journal of Drug and Alcohol Abuse, 43(3): 271-280.https://doi.org/10.1080/00952990.2016.1198797
  • Solomon, M., J. Simon, & H. Kincaid (eds). Routledge Companion to the Philosophy of Medicine. Routledge: London, 2017.
  • Datta, S., Burns, J., Maughan-Brown, B., Darling, M., & Eyal, K. 2015. Risking it all for love? Resetting beliefs about HIV risk among low-income South African teens, Journal of Economic Behaviour and Organisation, 118. https://doi.org/10.1016/j.jebo.2015.02.020
  • Sharp, C., Dellis, A., Hofmeyr, A., Kincaid, H., & Ross, D. 2015. First evidence of comorbidity of problem gambling and other psychiatric problems in a representative urban sample of South Africa. Journal of Gambling Studies, 31(3):  679-694. https://doi.org/10.1007/s10899-014-9469-y
  • Tibesigwa, B. & Visser, M. 2015. Multiple and concurrent sex partnerships and social norms: Young adults’ sexual relationships in the metropolitan communities of Cape Town South Africa. Sexuality Research and Social Policy 12(4): 301-316.https://doi.org/10.1007/s13178-015-0200-2
  • Dellis, A., Sharp, C., Hofmeyr, A., Schwardmann, P., Spurrett, D., Rousseau, J., & Ross, D. 2014. Criterion-related and construct validity of the Problem Gambling Severity Index in a sample of South African gamblers. South African Journal of Psychology, 44(2): 243-257. https://doi.org/10.1177/0081246314522367
  • Ross, D. Syndrome stabilization in psychiatry: Pathological gambling as a case study. In H. Kincaid & J. Sullivan, eds., Classifying Psychopathology. Cambridge, MA: MIT Press. 2014. pp. 195-208.
  • Dellis, A., Spurrett, D., Hofmeyr, A., Sharp, C., & Ross, D. 2013. Gambling Participation and Problem Gambling Severity among Rural and Peri-Urban Poor South African Adults in KwaZulu-Natal. Journal of Gambling Studies, 29(3): 417-433. https://doi.org/10.1007/s10899-012-9324-y
  • Kincaid, H., Daniels, R., Dellis, A., Hofmeyr, A., Rousseau, J., Sharp, C., & Ross, D. 2013. A Taxometric Analysis of Problem Gambling Data from a South African National Urban Sample. Journal of Gambling Studies, Vol. 29(3): 377-392.  https://doi.org/10.1007/s10899-012-9316-y
  • Ross, D. The picoeconomics of gambling addiction and supporting neural mechanisms. In N. Levy, ed., Addiction and Self Control. Oxford University Press. 2013. pp. 38-47.
  • Sharp, C., Steinberg, L., Yaroslavsky, I., Hofmeyr, A., Dellis, A., Ross, D., & Kincaid, H. 2012. An Item Response Theory Analysis of the Problem Gambling Severity Index. Assessment, 19(2): 167-175.https://doi.org/10.1177/1073191111418296  
  • Ross, D. Addictive, compulsive and other counter-normative consumption. In V. Wells & G. Foxall, eds., New Developments in Consumer Behavior. Edward Elgar. 2012. pp. 323-360.
  • Ross, D. Decision-making and substance abuse: A South African perspective. In G. Ellis, D. Stein, K. Thomas and E. Meintjes, eds., Substance use and abuse in South Africa. Cape Town: UCT Press. 2012. pp. 185-200.
  • Collins, P., Stein, D., Pretorius, A., Sinclair, H., Ross, D., Barr, G., Hofmeyr, A. ,Sharp, C., Spurrett, D., Rousseau, J., Ainslie, G., Dellis, A., Kincaid, H., & Bak, N. 2011. Addressing Problem Gambling: South Africa’s National Responsible Gambling Programme. South African Medical Journal, 101(10): 722-723._http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0256-95742011001000022
  • Hofmeyr, A., Ainslie, G., Charlton, R., & Ross, D. 2011. The relationship between addiction and reward bundling: An experiment comparing smokers and non-smokers. Addiction, Vol. 106(2), pp. 402-409. https://doi.org/10.1111/j.1360-0443.2010.03166.x