Does the Use of Mobile Devices (Tablets and Smartphones) Affect Stated Choice Behavior in Web Surveys? An Application to Environmental Valuation

Web surveys are becoming increasingly popular in survey research. Compared with face-to-face, telephone and mail surveys, web surveys may contain a different and new source of measurement error and bias: the type of device that respondents use to answer the survey questions. To the best of our knowledge, this is the first study that tests whether the use of mobile devices affects survey characteristics and stated preferences in a web-based choice experiment. The web survey was carried out in Germany with 3,400 respondents, of which 12 per cent used a mobile device (i.e. tablet or smartphone), and comprised a stated choice experiment on externalities of renewable energy production using wind, solar and biomass. Our main finding is that survey characteristics such as interview length and acquiescence tendency are affected by the device used. In contrast to what might be expected, we find that, compared with respondents using desktop computers and laptops, mobile device users spent more time to answer the survey and are less likely to be prone to acquiescence bias. In the choice experiment, mobile device users tended to be more consistent in their stated choices, and there are differences in willingness to pay between both subsamples.

Do we need antiplatelet therapy in thrombocytosis? Pro. Diagnostic and pathophysiologic considerations for a treatment choice.

Thrombocytosis (defined as platelets >450 x 10(9)/l) has several aetiologies. After having excluded spurious thrombocytosis (e. g., due to microspherocytes, schistocytes, cryoglobulins, or bacteria), the differential diagnosis of true thrombocytosis encompasses secondary causes (as diverse as inflammation, infection, malignancy, iron deficiency, or asplenia), primary hereditary (rare forms of familial thrombocytosis) and primary acquired entities (either in the context of a myelodysplastic syndrome or more frequently a myeloproliferative neoplasia). This manuscript addresses the following aspects: 1) diagnostic approach to thrombocytosis; 2) various mechanisms leading to a high platelet count; 3) potential of some of these mechanisms to modulate platelet function, producing hyper-reactive platelets and thus exerting a direct impact on the thrombotic risk; 4) indication of anti-thrombotic treatment in patients with thrombocytosis. There is a single prospective randomized clinical trial showing the benefit of acetyl-salicylic acid in polycythaemia vera. For other types of primary thrombocytosis and for secondary forms, treatment decisions have to be individualized according to the patient thrombotic and bleeding risks, taking into account the mechanism causing thrombocytosis. This manuscript discusses experimental and clinical data suggesting that besides patients with essential thrombocythaemia and other forms of primary thrombocytosis also those with thrombocytosis in the context of chronic inflammation, malignancy, or exposure to high altitude might benefit from anti-platelet treatment.

ROBREG: Stata module providing robust regression estimators

robreg provides a number of robust estimators for linear regression models. Among them are the high breakdown-point and high efficiency MM-estimator, the Huber and bisquare M-estimator, and the S-estimator, each supporting classic or robust standard errors. Furthermore, basic versions of the LMS/LQS (least median of squares) and LTS (least trimmed squares) estimators are provided. Note that the moremata package, also available from SSC, is required.

Public service motivation and rational choice modeling

While most previous research has considered public service motivation (PSM) as the only motivational factor predicting (public) job choice, the authors present a novel, rational choice-based model which includes three motivational dimensions: extrinsic, enjoyment-based intrinsic and prosocial intrinsic. Besides providing more accurate person-job fit predictions, this new approach fills a significant research gap and facilitates future theory building.

A double-edged sword: How perceived variety and perceived choice difficulty jointly determine consumers’ satisfaction with a customized product

High variety assortments are a double-edged sword. On one hand perceiving large variety is attractive, on the other hand choosing from it can cause perceived choice difficulty. Using mass-customizations tools our two studies show how both antipodal processes jointly determine consumers’ satisfaction with the customized product.

The effect of male coloration on female mate choice in closely related Lake Victoria cichlids (Haplochromis nyererei complex)

We studied the effect of male coloration on interspeciÆc female mate choice in two closely related species of haplochromine cichlids from Lake Victoria. The species differ primarily in male coloration. Males of one species are red, those of the other are blue. We re- corded the behavioral responses of females to males of both species in paired male trials under white light and under monochromatic light, under which the interspecific differences in coloration were masked. Females of both species exhibited species-assortative mate choice when colour differences were visible, but chose non-assortatively when colour differences were masked by light conditions. Neither male behaviour nor overall female response frequencies differed between light treatments. That female preferences could be altered by manipulating the perceived colour pattern implies that the colour itself is used in interspecific mate choice, rather than other characters. Hence, male coloration in haplochromine cichlids does underlie sexual selection by direct mate choice, involving the capacity for individual assessment of potential mates by the female. Females of both species responded more frequently to blue males under monochromatic light. Blue males were larger and displayed more than red males. This implies a hierarchy of choice criteria. Females may use male display rates, size, or both when colour is unavailable. Where available, colour has gained dominance over other criteria. This may explain rapid speciation by sexual selection on male coloration, as proposed in a recent mathematical model.

Direct mate choice maintains diversity among sympatric cichlids in Lake Victoria

Mate choice may play an important role in animal speciation. The haplochromine cichlids of Lake Victoria are suitable to test this hypothesis. Diversity in ecology, coloration and anatomy evolved in these fish faster than postzygotic barriers to gene flow, and little is known about how this diversity is maintained. It was tested whether recognizable forms are selection-maintained morphs or reproductively isolated species by investigating in the field reproductive timing, location of spawning sites, and mate choice behaviour. There was a large interspecific overlap in timing of breeding and location of spawning sites, which was largest in members of the same genus. Behavioural mate choice of such closely related taxa was highly assortative, such that it is likely that they are sexually isolated species and that direct mate choice is the major force that directs gene flow and maintains form diversity. The results differ from what is known about recent radiations of other lacustrine fish groups where speciation seems to be driven by diverging microhabitat preferences or diverging timing of reproduction, but are in agreement with predictions from models of speciation by diverging mate preferences.

Training Module for ALS Moderators: Report on conceptual and methodological aspects of the first workshop in Pemba Metuge, Cabo Delgado, Mozambique, April 2005

Report on conceptual and methodological aspects of the first workshop for training moderators and trainers in ALS and sustainable management of natural resources, in Pemba Metuge, Cabo Delgado, Mozambique, April 2005.

A common mechanism underlying food choice and social decisions

People make numerous decisions every day including perceptual decisions such as walking through a crowd, decisions over primary rewards such as what to eat, and social decisions that require balancing own and others’ benefits. The unifying principles behind choices in various domains are, however, still not well understood. Mathematical models that describe choice behavior in specific contexts have provided important insights into the computations that may underlie decision making in the brain. However, a critical and largely unanswered question is whether these models generalize from one choice context to another. Here we show that a model adapted from the perceptual decision-making domain and estimated on choices over food rewards accurately predicts choices and reaction times in four independent sets of subjects making social decisions. The robustness of the model across domains provides behavioral evidence for a common decision-making process in perceptual, primary reward, and social decision making.

Habitat Choice and Female Preference in a Polymorphic Stickleback Population

Background: A small pond, c. 90 years old, near Bern, Switzerland contains a population of threespine stickleback (Gasterosteus aculeatus) with two distinct male phenotypes. Males of one type are large, and red, and nest in the shallow littoral zone. The males of the other are small and orange, and nest offshore at slightly greater depth. The females in this population are phenotypically highly variable but cannot easily be assigned to either male type. Question: Is the existence of two sympatric male morphs maintained by substrate-associated male nest site choice and facilitated by female mate preferences? Organisms: Male stickleback caught individually at their breeding sites. Females caught with minnow traps. Methods: In experimental tanks, we simulated the slope and substrate of the two nesting habitats. We then placed individual males in a tank and observed in which habitat the male would build his nest. In a simultaneous two-stimulus choice design, we gave females the choice between a large, red male and a small, orange one. We measured female morphology and used linear mixed effect models to determine whether female preference correlated with female morphology. Results: Both red and orange males preferred nesting in the habitat that simulated the slightly deeper offshore condition. This is the habitat occupied by the small, orange males in the pond itself. The proportion of females that chose a small orange male was similar to that which chose a large red male. Several aspects of female phenotype correlated with the male type that a female preferred.