Testing construct validity of verbal versus numerical measures of preference uncertainty in contingent valuation

The numerical certainty scale (NCS) and polychotomous choice (PC) methods are two widely used techniques for measuring preference uncertainty in contingent valuation (CV) studies. The NCS follows a numerical scale and the PC is based on a verbal scale. This report presents results of two experiments that use these preference uncertainty measurement techniques. The first experiment was designed to compare and contrast the uncertainty scores obtained from the NCS and the PC method. The second experiment was conducted to test a preference uncertainty measurement scale that combines verbal expressions with numerical and graphical interpretations: a composite certainty scale (CCS). The construct validity of the certainty scores obtained from these three techniques was tested by estimating three separate ordered probit regression models. The results of the study can be summarised in three key findings. First, the PC method generates a higher proportion of ‘yes’ responses than the conventional dichotomous choice elicitation format. Second, the CCS method generates a significantly higher proportion of certain responses than the NCS and the PC methods. Finally, the NCS method performs poorly in terms of construct validity. Overall, the verbal measures perform better than the numerical measure. The CCS is a promising method to measure preference uncertainty in CV studies. To better understand its strengths and weaknesses however, further empirical applications are needed.preference uncertainty, contingent valuation, numerical certainty scale, polychotomous choice method, composite certainty scale, climate change, Australia., Environmental Economics and Policy, Research Methods/ Statistical Methods, Q51, Q54,

A cognitive psychological approach of analyzing preference uncertainty in contingent valuation

The sources of preference uncertainty in contingent valuation (CV) studies have rarely been investigated from a theoretical standpoint. This paper proposes a holistic theoretical framework of preference uncertainty that combines microeconomic theory with the theories of cognitive psychology. Empirical testing of the proposed theoretical model was carried out in Australia in the context of a national ‘Carbon Pollution Reduction Scheme (CPRS)’ to be introduced in 2010. Two separate ordered probit models for a certainty score associated with CV ‘Yes’ and ‘No’ responses were estimated. The results of the estimated regression models provide evidence supporting the hypotheses drawn from the theoretical model.Contingent valuation, preference uncertainty, cognitive uncertainty, climate change, Australia,

Estimating non-market values under scenario and policy ambiguity: the case of climate change mitigation in Australia

This report proposes an extension to existing models of non-expected utility (NEU) in the stated preference (SP) literature. The extension incorporates the impact of multiple sources of ambiguity in individual decision making behaviour. Empirical testing of the proposed decision model was carried out in Australia using a dichotomous choice contingent valuation study of a national carbon pollution reduction scheme (CPRS). The results of the study demonstrate that subjective expectations of the context scenario and subjective policy expectations are important determinants of individual decision making in a stated preference framework. The results of the study also demonstrate that decision weight functions are non-linear (quadratic) in subjective scenario expectations and subjective policy expectation. Although evidence was found to link willingness to pay to scenario ambiguity, policy ambiguity was found to have no statistically significant influence on individual decision making.non-expected utility, scenario ambiguity, policy ambiguity, climate change, Australia, Environmental Economics and Policy, Resource /Energy Economics and Policy, C93-D81,

Household perceptions of climate change and preferences for mitigation action: the case of the Carbon Pollution Reduction Scheme in Australia

This study aims to show how Australian households perceive climate change and what they are prepared to do to reduce the harmful effects of climate change. A web-based survey in November 2008 asked approximately 600 New South Wales households about their willingness to pay additional household expenses caused by the Carbon Pollution Reduction Scheme (CPRS) proposed by the Australian government. The Contingent Valuation Method (CVM), a widely used non-market valuation technique, was applied. Results of the study show there is a positive demand to mitigate climate change in Australia resulting from a wish to avoid climate change. Households’ willingness to pay (WTP) for climate change was, however, significantly curbed as households was uncertain about the extent of climate change and whether climate change policies are effective. Australian household support for the CPRS is influenced by schemes of other major greenhouse gas emitting countries (global co-operation). Only when people who didn’t answer the survey are assumed to value climate change mitigation the same as people who did answer the survey, do the benefits of the CPRS, as estimated by respondents’ WTP, exceed its costs.Contingent valuation, climate change, Carbon Pollution Reduction Scheme, willingness to pay, uncertainty, Australia, Environmental Economics and Policy, Resource /Energy Economics and Policy,

Modelling the Impact of Perceived Connectivity on the Intention to Use Social Media: Discovering Mediating Effects and Unobserved Heterogeneity

Early research examined the direct effect of perceived connectivity (PC) on intention to adopt information systems. In this study, we extend that research stream by examining the mediating effects of perceived enjoyment (PE) and perceived playfulness (PP) on the relationship between PC and the intention to use social media within the workplace. To test our proposed model, we collected data from 2,556 social media users from Australia, Canada, India, the UK, and the US. We applied the REBUS-PLS algorithm, a response-based method for detecting unit segments in PLS path modelling and assessing the unobserved heterogeneity in the data sample. Based on the strength of effects, the algorithm automatically detected two groups of users sharing the same intentions to use social media. A post hoc analysis of each group was done using contextual and demographic variables including geographic location, country, age, education and gender. Implications for practice and research are discussed

Association study and expression analysis of stearoyl Co-A desaturase as a candidate gene for fatty acid composition in Indonesian crossbred chickens

Background and Objective: The stearoyl-CoA desaturase (SCD) gene encodes an enzyme involved in fatty acid (FA) biosynthesis. The aim of the present study was to investigate the association and expression of SCD as a candidate gene for FA composition in Indonesian crossbred chickens. Materials and Methods: Sixty-two Indonesian crossbred, unsexed chickens (F2 Kampung×broilers) were used. FA composition was measured at 12 weeks of age from thigh meat of crossbred chicken. Results: A single nucleotide polymorphism in coding region c.17492542 C>G of SCD was associated with FA composition, including both unsaturated [linoleic (C18:2n6c) and eicosadienoic (C20:2) acids] and saturated [lauric acid (C12:0)] forms. SCD mRNA expression analysis in liver revealed 6 chickens with extremely high and low FA compositions, of them, high FA birds (n = 3) had higher unsaturated and lower saturated FAs, while the low FA group (n = 3) had lower unsaturated and higher saturated FA levels. SCD expression was higher (p<0.05) in tissues collected from high FA chickens than low FA chickens. Conclusion:These results will improve the understanding of SCD function in FA composition and will shed light on SCD as a potential candidate in the selection of chickens with higher levels of unsaturated and lower levels of saturated FA

Disease cycle of Austropuccinia psidii on Eucalyptus globulus and Eucalyptus obliqua leaves of different rust response phenotypes

Myrtle rust poses a significant biosecurity threat to Australia with potential for long-term damaging impacts on nativeflora and plant industries. This study describes the disease cycle of Austropuccinia psidii, the myrtle rust pathogen, in Eucalyptus globulus and Eucalyptus obliqua, two commercially and ecologically important species from different sub-genera of Eucalyptus. Ontogeny and morphology of infection structures of A. psidii on plants of both Eucalyptus species with different rust response phenotypes, i.e. completely resistant, hypersensitive and highly susceptible, were investigated. Plants were inoculated with single-uredinium-derived urediniospores and examined by scanning electron microscopy. No differences between rust response phenotypes were observed in germination of urediniospores, formation of appressoria or length of germ tubes. The growth of germ tubes had no affinity towards stomata of either species. Histological observations indicated direct penetration by infection pegs through the leaf cuticle and no penetration beyond the epidermis on rust-resistant E. obliqua.Eucalyptus obliqua plants that were identified as susceptible to A. psidii at 3- and 6-months-old showed no disease when reinoculated with A. psidii at 12-months-old; this indicated possible early acquisition of adult plant resistance to A. psidii in this species. In the susceptible phenotype of E. globules rust inoculation led to rapid colonization of leaf parenchyma cells with the disease cycle completed within 10 days. These findings provide valuable insights into host–pathogen interactions in the Eucalyptus–A. psidii pathosystem,which might be useful for the development of effective rust control strategies across Eucalyptus subgenera

Risk Factors for Kala-Azar in Bangladesh

Since 1990, South Asia has experienced a resurgence of kala-azar (visceral leishmaniasis). To determine risk factors for kala-azar, we performed cross-sectional surveys over a 3-year period in a Bangladeshi community. By history, active case detection, and serologic screening, 155 of 2,356 residents had kala-azar with onset from 2000 to 2003. Risk was highest for persons 3–45 years of age, and no significant difference by sex was seen. In age-adjusted multivariable models, 3 factors were identified: proximity to a previous kala-azar patient (odds ratio [OR] 25.4, 95% confidence interval [CI] 15–44 within household; OR 3.2 95% CI 1.7–6.1 within 50 m), bed net use in summer (OR 0.7, 95% CI 0.53–0.93), and cattle per 1,000 m2 (OR 0.8, 95% CI 0.70–0.94]). No difference was seen by income, education, or occupation; land ownership or other assets; housing materials and condition; or keeping goats or chickens inside bedrooms. Our data confirm strong clustering and suggest that insecticide-treated nets could be effective in preventing kala-azar

The impact of type 2 diabetes on health related quality of life in Bangladesh: results from a matched study comparing treated cases with non-diabetic controls

Background Little is known about the association between diabetes and health related quality of life (HRQL) in lower-middle income countries. This study aimed to investigate HRQL among individuals with and without diabetes in Bangladesh. Methods The analysis is based on data of a case-control study, including 591 patients with type 2 diabetes (cases) who attended an outpatient unit of a hospital in Dhaka and 591 age -and sex-matched individuals without diabetes (controls). Information about socio-demographic characteristics, health conditions, and HRQL were assessed in a structured interview. HRQL was measured with the EuroQol (EQ) visual analogue scale (VAS) and the EQ five-dimensional (5D) descriptive system. The association between diabetes status and quality of life was examined using multiple linear and logistic regression models. Results Mean EQ-VAS score of patients with diabetes was 11.5 points lower (95 %-CI: −13.5, −9.6) compared to controls without diabetes. Patients with diabetes were more likely to report problems in all EQ-5D dimensions than controls, with the largest effect observed in the dimensions ‘self-care’ (OR = 5.9; 95 %-CI: 2.9, 11.8) and ‘mobility’ (OR = 4.5; 95 %-CI: 3.0, −6.6). In patients with diabetes, male gender, high education, and high-income were associated with higher VAS score and diabetes duration and foot ulcer associated with lower VAS scores. Other diabetes-related complications were not significantly associated with HRQL. Conclusions Our findings suggest that the impact of diabetes on HRQL in the Bangladeshi population is much higher than what is known from western populations and that unlike in western populations comorbidities/complications are not the driving factor for this effect