Scalable Inference of Customer Similarities from Interactions Data using Dirichlet Processes

Under the sociological theory of homophily, people who are similar to one another are more likely to interact with one another. Marketers often have access to data on interactions among customers from which, with homophily as a guiding principle, inferences could be made about the underlying similarities. However, larger networks face a quadratic explosion in the number of potential interactions that need to be modeled. This scalability problem renders probability models of social interactions computationally infeasible for all but the smallest networks. In this paper we develop a probabilistic framework for modeling customer interactions that is both grounded in the theory of homophily, and is flexible enough to account for random variation in who interacts with whom. In particular, we present a novel Bayesian nonparametric approach, using Dirichlet processes, to moderate the scalability problems that marketing researchers encounter when working with networked data. We find that this framework is a powerful way to draw insights into latent similarities of customers, and we discuss how marketers can apply these insights to segmentation and targeting activities

Anomalies in Estimates of Cross-Price Elasticities for Marketing Mix Models: Theory and Empirical Test

We investigate the theoretical possibility and empirical regularity of two troublesome anomalies that frequently arise when cross-price elasticities are estimated for a set of brands expected to be substitutes. These anomalies are the occurrence of: (a) negatively signed cross-elasticities; and (b) sign asymmetries in pairs of cross price elasticities. Drawing upon the Slutsky equation from neoclassical demand theory, we show how and why these anomalies may occur when cross elasticities are estimated for pairs of brands that are substitutes. We empirically examine these issues in the context of the widely used Multiplicative Competitive Interaction (MCI) and Multinomial Logit (MNL) specifications of the fully extended attraction models (Cooper and Nakanishi 1988). Utilizing a database of store-level scanner data for 25 categories and 127 brands of frequently purchased branded consumer goods, we find that about 18% of a total of 732 cross elasticity estimates are negative and approximately 40% of the 366 pairs of cross elasticities are sign asymmetric. Finally, we find that the occurrence of negatively signed cross elasticities can be partially explained by a set of hypothesized relationships between cross-price elasticities and brand share and elasticities of income and category demand.

Health shocks, coping strategies and foregone healthcare among agricultural households in Kenya

Risks are a central part of life for households in low-income countries and health shocks in particular are associated with poverty. Formal mechanisms protecting households against the financial consequences of shocks are largely absent, especially among poor rural households. Our aim is to identify the relative importance of health shocks and to explore factors associated with coping behaviour and foregone care. We use a cross-sectional survey among 1226 randomly selected agricultural households in Kenya. In our sample, illness and injury shocks dominate all other shocks in prevalence. Almost 2% of households incurred catastrophic health expenditure in the last year. Using a probit model we identified the main coping strategies associated with facing a health shock: (1) use savings, (2) sell assets and (3) ask for gifts or loans. One in five households forewent necessary care in the last 12 months. We conclude that health shocks pose a significant risk to households. Implementing pre-payment or saving mechanisms might help protect households against the financial consequences of ill health. Such mechanisms, however, should take into account the competing shocks that agricultural households face, making it almost impossible to reserve a share of their limited resources for the protection against health shocks only

Does health care utilization match needs in Africa? Challenging conventional needs measurement

Abstract. An equitable distribution of health care use, distributed according to people’s needs instead of ability to pay, is an important goal featuring on many health policy agendas worldwide. However, relatively little is known about the extent to which this principle is violated across socio-economic groups in Sub Saharan Africa (SSA). We examine cross-country comparative micro-data from eighteen SSA countries and find that (a) considerable inequalities in health care use exist and vary across countries, but that (b) identifying the extent to which these inequalities are unfair, i.e. do not correspond to inequalities in need, is not straightforward to ascertain with the conventional tools. These tools include rank-based measures such as the concentration index and the index of inequity. The two main concerns when using conventional tools to measure equity are (i) the reporting heterogeneity in self-reported health variables across socio-economic groups and (ii) the weak relationship between need and use. We show that the use of subjective self-reports of health leads to much lower measured degrees of socio-economic inequalities than those obtained using more objective indicators. This leads to an underestimation of the degree of inequity when using self-reported health measures. The observed weak relationship between indicators of ill-health and use of health care does not appear to provide an estimate of the adequate response to needs, which further puts a downward bias on equity measures. In all countries, apart from the more developed Mauritius, health care use is distributed according to wealth rather than to need. A better match of needs and use is realized in those countries with better governance and more physicians but, perhaps surprisingly, not those with greater urbanization. Given the importance of equity in many health policies worldwide, it is vital to develop more robust equity measures relevant to low income settings

Reactivity to human papillomavirus type 16 Ll virus-like particles in sera from patients with genital cancer and patients with carcinomas at five different extragenital sites

A retrospective seroepidemiologic study was performed to examine the association between human papillomaviruses (HPV) 16 infection and carcinomas of the oropharynx, the oesophagus, penis and vagina. Sera were selected from the serum bank from the Antoni van Leeuwenhoek Hospital (Netherlands Cancer Institute) and the Slotervaart Hospital in Amsterdam, the Netherlands. Presence of HPV 16 specific antibody was assessed using HPV 16 L1 capsids. Sera positive for HPV 16 capsid antibody were further tested for antibody against HPV 16 E7 peptides. Prevalence of antibody against H PV 16 L1 capsids among both the negative control group without cancer and the negative control group with gastric cancer was 18%, while seroprevalence among the control group of patients with HPV-associated cervical squamous cell carcinoma was 47% (P < 0.001). Among the patients with penile squamous cell carcinoma seroprevalence was 38% (P < 0.001), among patients with oropharyngeal carcinoma 33% (P = 0.04) and among patients with oesophageal squamous cell carcinoma 14% (P = 0.7). The serological evidence for association between HPV 16 infection and both oropharyngeal carcinoma and penile carcinoma was established. The conclusion that no association was found between the presence of antibody against HPV 16 L1 capsids and oesophageal squamous cell carcinoma was in accordance with results of other studies carried out in the Netherlands using HPV DNA technology. In the subjects with HPV 16 L1 capsid antibody, no association was found between the antibody against HPV 16 E7 and clinical outcome

Effects of a smartphone application on maternal health knowledge and dietary diversity among pregnant women in india:A randomized single center pilot study

Background:India contributes to one-fifth of infant and maternal deaths globally. Healthy lifestyles during pregnancy combined with good quality health care can help to avoid many maternal and neonatal deaths. Access to appropriate information is important for developing or maintaining a healthy lifestyle. The increased coverage of smartphones across low- and middle-income countries (LMICs) has given rise to smartphone apps supporting healthy pregnancies. The objective of this study is to evaluate the effects of the smartphone application Together For Her on maternal health knowledge and dietary diversity among pregnant Indian women. Methods:We ran a randomised single-centre pilot study in a private hospital in Maharashtra, India. We randomly selected pregnant women at $20 weeks of gestation who were invited to download the application, in addition to regular antenatal care. The control group only received regular antenatal care. Knowledge about a healthy lifestyle during pregnancy, self-reported dietary diversity and individual characteristics were collected via telephone interviews at baseline (T0), midline (T0 + 4 weeks) and endline (T0 + 12 weeks). Results:Complete data were collected for 179 respondents (intervention:94; control:85). Respondents in the intervention group showed larger increases in their knowledge over the 12-week study period, with an overall knowledge increase of 13.4 percentage points (P&lt;0.001). The largest effects were found in the modules anaemia, breastfeeding and skin-to-skin contact. Self-reported diversity in nutritional intake also improved significantly more in the intervention group than in the control group. Conclusions:Smartphone applications can effectively supplement antenatal care by increasing women’s knowledge about a healthy lifestyle during pregnancy, which is likely to reduce the risk of adverse maternal health outcomes. Future research includes the roll-out of a larger multi-centre RCT to assess the effect of the smartphone application on health outcomes.</p