Estimating the Causal Effects of Marketing Interventions Using Propensity Score Methodology

Propensity score methods were proposed by Rosenbaum and Rubin [Biometrika 70 (1983) 41--55] as central tools to help assess the causal effects of interventions. Since their introduction more than two decades ago, they have found wide application in a variety of areas, including medical research, economics, epidemiology and education, especially in those situations where randomized experiments are either difficult to perform, or raise ethical questions, or would require extensive delays before answers could be obtained. In the past few years, the number of published applications using propensity score methods to evaluate medical and epidemiological interventions has increased dramatically. Nevertheless, thus far, we believe that there have been few applications of propensity score methods to evaluate marketing interventions (e.g., advertising, promotions), where the tradition is to use generally inappropriate techniques, which focus on the prediction of an outcome from background characteristics and an indicator for the intervention using statistical tools such as least-squares regression, data mining, and so on. With these techniques, an estimated parameter in the model is used to estimate some global ``causal'' effect. This practice can generate grossly incorrect answers that can be self-perpetuating: polishing the Ferraris rather than the Jeeps ``causes'' them to continue to win more races than the Jeeps $\Leftrightarrow$ visiting the high-prescribing doctors rather than the low-prescribing doctors ``causes'' them to continue to write more prescriptions. This presentation will take ``causality'' seriously, not just as a casual concept implying some predictive association in a data set, and will illustrate why propensity score methods are generally superior in practice to the standard predictive approaches for estimating causal effects.Comment: Published at http://dx.doi.org/10.1214/088342306000000259 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Effective responder communication improves efficiency and psychological outcomes in a mass decontamination field experiment: implications for public behaviour in the event of a chemical incident

The risk of incidents involving mass decontamination in response to a chemical, biological, radiological, or nuclear release has increased in recent years, due to technological advances, and the willingness of terrorists to use unconventional weapons. Planning for such incidents has focused on the technical issues involved, rather than on psychosocial concerns. This paper presents a novel experimental study, examining the effect of three different responder communication strategies on public experiences and behaviour during a mass decontamination field experiment. Specifically, the research examined the impact of social identity processes on the relationship between effective responder communication, and relevant outcome variables (e.g. public compliance, public anxiety, and co-operative public behaviour). All participants (N = 111) were asked to visualise that they had been involved in an incident involving mass decontamination, before undergoing the decontamination process, and receiving one of three different communication strategies: 1) Health-focused explanations about decontamination, and sufficient practical information; 2) No health-focused explanations about decontamination, sufficient practical information; 3) No health-focused explanations about decontamination, insufficient practical information. Four types of data were collected: timings of the decontamination process; observational data; and quantitative and qualitative self-report data. The communication strategy which resulted in the most efficient progression of participants through the decontamination process, as well as the fewest observations of non-compliance and confusion, was that which included both health-focused explanations about decontamination and sufficient practical information. Further, this strategy resulted in increased perceptions of responder legitimacy and increased identification with responders, which in turn resulted in higher levels of expected compliance during a real incident, and increased willingness to help other members of the public. This study shows that an understanding of the social identity approach facilitates the development of effective responder communication strategies for incidents involving mass decontamination

Recognising and understanding collective resilience in crowds of survivors

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Issues affecting mental health at a fly‐in‐fly‐out mine site: A subjective impact ratings approach

Around a third of fly-in fly-out (FIFO) workers in Australia experience relatively high levels of psychological distress. Although a wide range of associated workplace stressors have been proposed in this context, it is unclear to what extent FIFO workers perceive these stressors as having an impact on their mental health. Identifying the issues that workers perceive as having the greatest impact on their mental health can guide the development of interventions in this area. Thus, this cross-sectional study sampled 742 FIFO workers from a large mine site in Australia to identify which workplace issues were perceived to have the greatest negative impact on their mental health. Of the 32 issues measured, we found that the top ranked issues related to a lack of control at work, lack of sleep, missing home, and poor physical health. These key issues also predicted poorer recent mental health. Based on these findings, several recommendations are put forward for future on-site wellness promotion programs, including (a) providing workers with more control and autonomy in their work roles, (b) improving sleep hygiene, (c) facilitating regular communication with family and loved ones, and (d) introducing exercise programs and supporting a healthy diet. This type of proactive consultative approach to mental health issues at FIFO sites cannot only mitigate the increased risk of poor mental health but also foster a more cohesive workplace culture

Psychometric properties of an instrument for assessing the experience of patients treated with inhaled insulin: the Inhaled Insulin Treatment Questionnaire (IITQ)

<p>Abstract</p> <p>Background</p> <p>Along with general measures of treatment satisfaction, treatment-specific and device-specific treatment satisfaction should be assessed in clinical trials, because these latter measures may be more strongly correlated with clinical outcomes.</p> <p>Methods</p> <p>Study participants were 1076 adults (type 1 = 509, type 2 = 567) in clinical trials of Technosphere Insulin^®, who completed the SF-36 health-related quality of life questionnaire and the Inhaled Insulin Treatment Questionnaire (IITQ), a new instrument assessing diabetes worries, perceptions of insulin therapy, treatment satisfaction, treatment preference, and inhaler performance. The IITQ was administered twice prior to treatment initiation in the clinical trials, 1-2 weeks apart, and several times during the trials. Inhaler performance was assessed at follow-up visits, after participants had used the device.</p> <p>Results</p> <p>IITQ subscales had acceptable reliability (alpha = 0.68-0.87, median 0.83) and test-retest correlations (intra-class correlation coefficient = 0.67-0.90, median 0.82); floor effects (0.2-2.8%) and ceiling effects (0-9.3%) were minimal. Reliabilities for inhaler performance measures were acceptable (alpha = 0.73-0.90, median 0.85); there were no floor effects (0.0%) and ceiling effects (4.9-39.0%) were moderate. There were several modest associations between IITQ scores and measures of health status. Diabetes worries were lower for participants who had better mental health (type 2) and for those with higher BMI; perceptions of insulin therapy were more favorable for participants who had better physical and mental health; treatment satisfaction was higher for patients who had lower BMI (type 2), lower A1c levels, and better physical health (type 2); treatment preference was higher for patients with lower BMI (type 2) and better mental health (type 1).</p> <p>Conclusions -</p> <p>Preliminary findings suggest that the IITQ is a comprehensive, reliable measure of the experience of patients treated with inhaled insulin.</p

Visualization of hydrogen injection in a scramjet engine by simultaneous PLIF imaging and laser holographic imaging

Flowfield characterization has been accomplished for several fuel injector configurations using simultaneous planar laser induced fluorescence (PLIF) and laser holographic imaging (LHI). The experiments were carried out in the GASL-NASA HYPULSE real gas expansion tube facility, a pulsed facility with steady test times of about 350 microsec. The tests were done at simulated Mach numbers 13.5 and 17. The focus of this paper is on the measurement technologies used and their application in a research facility. The HYPULSE facility, the models used for the experiments, and the setup for the LHI and PLIF measurements are described. Measurement challenges and solutions are discussed. Results are presented for experiments with several fuel injector configurations and several equivalence ratios