Understanding the Impact of Male Circumcision Interventions on the Spread of HIV in Southern Africa

BACKGROUND: Three randomised controlled trials have clearly shown that circumcision of adult men reduces the chance that they acquire HIV infection. However, the potential impact of circumcision programmes--either alone or in combination with other established approaches--is not known and no further field trials are planned. We have used a mathematical model, parameterised using existing trial findings, to understand and predict the impact of circumcision programmes at the population level. FINDINGS: Our results indicate that circumcision will lead to reductions in incidence for women and uncircumcised men, as well as those circumcised, but that even the most effective intervention is unlikely to completely stem the spread of the virus. Without additional interventions, HIV incidence could eventually be reduced by 25-35%, depending on the level of coverage achieved and whether onward transmission from circumcised men is also reduced. However, circumcision interventions can act synergistically with other types of prevention programmes, and if efforts to change behaviour are increased in parallel with the scale-up of circumcision services, then dramatic reductions in HIV incidence could be achieved. In the long-term, this could lead to reduced AIDS deaths and less need for anti-retroviral therapy. Any increases in risk behaviours following circumcision, i.e. 'risk compensation', could offset some of the potential benefit of the intervention, especially for women, but only very large increases would lead to more infections overall. CONCLUSIONS: Circumcision will not be the silver bullet to prevent HIV transmission, but interventions could help to substantially protect men and women from infection, especially in combination with other approaches

Transaction decoupling: How price bundling affects the decision to consume

In today's marketplace, price bundling is widespread: Manufacturers and retailers routinely offer multiple products for a single, bundled price. Although the effects of price bundling on purchase behavior have been well researched, the effects of price bundling on postpurchase consumption behavior have received almost no attention. In this article, the authors build on the sunk cost literature (e.g., Thaler 1980, 1985) and predict that price bundling leads to a disassociation or "decoupling" of transaction costs and benefits, thereby reducing attention to sunk costs and decreasing a consumer's likelihood of consuming a paid-for service (e.g., a theater performance). Four studies show this to be the case. In two lab studies, the authors show that having a bundled four-day ski pass as opposed to four one-day ski tickets decreases a person's likelihood of skiing on the final day of a four-day ski vacation. They replicate this result in a field study, showing that multiperformance ticket holders are more likely to forgo a given theatrical performance than are single-performance ticket holders, all else held constant. In a final study, the authors show that the decreased attention to sunk costs brought about by price bundling can be either cognitively driven (i.e., it is difficult to allocate a single payment across multiple benefits) or motivationally driven (i.e., there is an underlying desire to avoid consumption). Their findings have practical implications for managers interested in predicting or influencing actual product consumption