One thousand, four hundred and six seniors were asked about their consumer spending preferences. While some could name a product spending preference, others could not. This study examines the characteristics that best distinguish those elders who are uninterested in spending on consumer products from those who choose product specific preferences. Discriminant function analyses show that age best distinguishes the non-interested group from the others, supporting a previous report by Walker and Schwenk (1991). Income and health status most reliably separate those whose most important spending priority is a recreational product from those most interested in basic needs or housing products. Those whose spending priority is a housing item tend to be home-owners who have lived in their residences for long periods of time. The results confirm that the heterogeneity among seniors documented in other areas (such as health and social characteristics) extends to their consumption preferences. The diversity in spending preferences can be understood in terms of a desire to enhance quality of life.

Numerous studies suggest that the clinical presentation of Alzheimer's disease (AD) is varied and that AD is thus a heterogeneous disorder. Evidence of this inter-individual variability has had an important impact on the approaches to the cognitive rehabilitation of AD, particularly in the early stages of the disease. Research has shown that, despite variable cognitive profiles, many preserved capabilities are observed in the first stages of AD and that the disease does not affect all cognitive functions globally. These preserved capabilities make it possible to apply cognitive interventions. However, numerous methodological difficulties are encountered in evaluating the effectiveness of these interventions, many of which are related to the heterogeneity of the deficits. The purpose of this article is to discuss this heterogeneity and its impact on methodological characteristics, especially participant selection and research design.

This article addresses the important issue of anchoring in contingent valuation surveys that use the double-bounded elicitation format. Anchoring occurs when responses to the follow-up dichotomous choice valuation question are influenced by the bid presented in the initial dichotomous choice question. Specifically, we adapt a theory from psychology to characterize respondents as those who are likely to anchor and those who are not. Using a model developed by Herriges and Shogren (1996), our method appears successful in discriminating between those who anchor and those who did not. An important result is that when controlling for anchoring – and allowing the degree of anchoring to differ between respondent groups – the efficiency of the double-bounded welfare estimate is greater than for the initial dichotomous choice question. This contrasts with earlier research that finds that the potential efficiency gain from the double-bounded questions is lost when anchoring is controlled for and that we are better off not asking follow-up questions.

Le peuplement des Crustacés de la zone hyporhéique d'un ruisseau des Pyrénées, le Nert, a été étudié pendant un an sur une aire de 30 m2 à 0,6 m et 1 m de profondeur. 35 espèces dont 20 stygobies ont été recensées. Ce peuplement est caractérisé par sa persistance due à la stabilité physique de l'environnement interstitiel. Il témoigne cependant d'une très forte hétérogénéité liée aux conditions hydrodynamiques qui règnent au sein des sédiments.

Restriction analysis of total DNAs from Leishmania donovani complex strains revealed heterogeneous distribution of kDNA fragments among the reference strains of L. donovani. The cloned kDNA fragments used as probes in the hybridisation analysis have proven useful for identifying and characterising L. donovani subspecies when screening newly isolated leishmanial parasites from patients, vectors and reservoir hosts. This genetic heterogeneity was confirmed by karyotyping by pulsed field gel electrophoresis of four L. donovani reference strains. A high degree of polymorphism was shown, affecting not only the chromosome size, but also their number.