A Semi-parametric Estimator of Willingness-to-pay Applied to Dichotomous Choice Contingent Valuation Data

The use of dichotomous choice questions (Are you willing to pay $x?) has been advocated as superior to open ended questions (What would you be willing to pay?) in contingent valuation studies of non‐market goods. A supplementary dichotomous choice question, raising or lowering the bid price depending on the initial response, gives increased precision. However, a problem with these methods is that identifying the mean willingness to pay (WTP) is more complex, and often conditional on making a distributional assumption. This paper will present a semi‐parametric method for estimating WTP without invoking any such assumptions, using the interval inherent in the double bounded format, and based on estimating the underlying hazard function for the distribution of WTP. An advantage of the approach over other non‐parametric methods is that it allows one to include respondent characteristics as determinants of the individual decisions, and does so within a computationally straightforward framework.     

Cost-effectiveness of metformin plus vildagliptin compared with metformin plus sulphonylurea for the treatment of patients with type 2 diabetes mellitus: a Portuguese healthcare system perspective

Objective:

To evaluate the cost-effectiveness of vildagliptin plus metformin vs generic sulphonylurea plus metformin in patients with type 2 diabetes mellitus, not controlled with metformin, from a Portuguese healthcare system perspective.

Methods:

A cost-effectiveness model was constructed using risk equations from the UK Prospective Diabetes Study Outcomes Model with a 10,000-patient cohort and a lifetime horizon. The model predicted microvascular and macrovascular complications and mortality in yearly cycles. Patients entered the model as metformin monotherapy failures and switched to alternative treatments (metformin plus basal-bolus insulin and subsequently metformin plus intensive insulin) when glycated hemoglobin A1c >7.5% was reached. Baseline patient characteristics and clinical variables were derived from a Portuguese epidemiological study. Cost estimates were based on direct medical costs only. One-way and probabilistic sensitivity analyses were conducted to test the robustness of the model.

Results:

There were fewer non-fatal diabetes-related adverse events (AEs) in patients treated with metformin plus vildagliptin compared with patients treated with metformin plus sulphonylurea (6752 vs 6815). Addition of vildagliptin compared with sulphonylurea led to increased drug acquisition costs but reduced costs of AEs, managing morbidities, and monitoring patients. Treatment with metformin plus vildagliptin yielded a mean per-patient gain of 0.1279 quality-adjusted life years (QALYs) and a mean per-patient increase in total cost of €1161, giving an incremental cost-effectiveness ratio (ICER) of €9072 per QALY. Univariate analyses showed that ICER values were robust and ranged from €4195 to €16,052 per QALY when different parameters were varied.

Limitations:

The model excluded several diabetes-related morbidities, such as peripheral neuropathy and ulceration, and did not model second events. Patients were presumed to enter the model with no diabetes-related complications.

Conclusion:

Treatment with metformin plus vildagliptin compared with metformin plus sulphonylurea is expected to result in a lower incidence of diabetes-related AEs and to be a cost-effective treatment strategy.     

Do changes in credit ratings of REITs affect their capital structure decisions?

Existing research has highlighted the high leverage ratio of Real Estate Investment Trusts (REITs). To the extent that credit rating is important to REITs when sourcing for capital from the public debt markets, our paper investigates the effect of changes in REIT credit ratings on capital structure decisions while controlling for endogeneity effects. Our results indicate that REITs that face the prospect of an imminent credit rating downgrade issue approximately 11% less debt net of equity as a percentage of total assets than other REITs. This effect is asymmetric in that positive rating outlooks do not have a significant impact on REIT capital structure activities.     

Corporate Social Responsibility and the Operationalization Challenge for Global Tourism Organizations

Tourism businesses have increasingly sought to contribute to society through corporate social responsibility (CSR) initiatives. Larger tourism organizations normally seek to institutionalize CSR under their corporate CSR policy and strategy that is common for their whole organization. This presents challenges for organizations with global operations. This article examines the operationalization of CSR policy by hotel properties in coastal destinations in Thailand. The research found that stakeholders other than the hotels played pivotal roles in the implementation of CSR programs and that there was a preference for involvement by hotels in local projects, over those situated elsewhere in the country or internationally. These hotels tended to partner with other non-hotel stakeholders to execute their external CSR programs and for these to be directed at social issues rather than environmental issues. Overall it was concluded that there are limits to the extent that corporate headquarters may direct the implementation of CSR.