Inference problems in life testing under multivariate normality

Modified maximum likelihood estimators of the parameters of a multivariate normal distribution are developed when the smallest or largest observations on one of the components are censored. These estimators are used to construct tests for means and correlation coefficients. The robustness of these tests to deviations from normality is investigated.     

Vacation farms and ecotourism in Saskatchewan, Canada

Vacation farms represent an increasingly significant rural diversification option for chronically unstable agriculture-based economies such as Saskatchewan. Concurrently, ecotourism is a rapidly expanding form of tourism which could serve to enhance the recreation product of such rural enterprises. Accordingly, a self-administered questionnaire was sent to all listed vacation farm operators in the province to obtain information on the provision of ecotourism opportunities. Just over one-half (n = 40) of all operations returned a completed questionnaire. Of 23 listed recreation options, wildlife viewing was cited as the activity most frequently undertaken by vacation farm visitors, followed by hunting, casual photography and touring. Wildlife viewing occurred most commonly during the spring and summer, with access to the resource occurring mainly on foot, and less so by horse and vehicle. Birds were the most important category of wildlife viewed, followed by mammals and plants; reptiles/amphibians, insects and fish were of only minor significance. It was evident that the sampled vacation farm operators possessed very little training in the area of ecotourism; few barriers or opportunities related to the latter were indicated. Appropriate recommendations include the provision of ecotourism training opportunities, stronger linkages between vacation farms and public spaces, and further investigation into the relationship between wildlife viewing and hunting activities.     

Gender differences in risk behaviour in financial decision-making: An experimental analysis

This paper examines whether gender differences in risk propensity and strategy in financial decision-making can be viewed as general traits, or whether they arise because of context factors. It presents the results of two computerised laboratory experiments designed to examine whether differences in risk preference and decision strategies are explained by the framing of tasks and level of task familiarity to subjects. The results show that females are less risk seeking than males irrespective of familiarity and framing, costs or ambiguity. The results also indicate that males and females adopt different strategies in financial decision environments but that these strategies have no significant impact on ability to perform. Because strategies are more easily observed than either risk preference or outcomes in day to day decisions, strategy differences may reinforce stereotypical beliefs that females are less able financial managers.     

Migration decision making and migration behavior in rural Kenya

Micro theories of migration have generally been tested with data which do not allow one to distinguish between the decision to move and the act of moving. The latter is usually treated as a proxy for the former. Using data from a two round survey of youth in rural Kenya we classify respondents as decision processors/nondecision processors from round one data, and determine who migrates over a nine month interval from round two data. Thirty-four percent of the sample are classified as decision processors and 25% as migrants, but decision processors were only slightly more likely to migrate than nondecision processors and more migrants actually came from the latter group.A simple model is developed to determine the extent to which the same factors that influence decision-processing influence who migrates. The model is tested using regression procedures by first treating decision-processing as the dependent variable then migration. The model explains 26% of the variance in who decides, but only 10% of the variance in who actually moved. Finally, separate analyses are done of the determinants of migration for decision processors and nondecision processors.     

Larval growth dynamics ofHemipyrellia ligurriens (Calliphoridae) andBoettcherisca formosensis (Sarcophagidae) in crowded and uncrowded cultures

Summary Larval growth patterns ofHemipyrellia ligurriens (Calliphoridae) andBoettcherisca formosensis (Sacophagidae) in crowded and uncrowded cultures were compared. Growth of the larvae followed a sigmoid curve. The highest larval growth rates were 0.33 and 0.36 mg h⁻¹ for uncrowded and crowdedH. ligurriens respectively. The corresponding figures were 2.38 and 1.23 mg h⁻¹ forB. formosensis. Larvae of both species attained maximum weight earlier in crowded cultures than in uncrowded cultures, although the final weights attained in crowded cultures were less. The earlier period of most rapid growth in both species was interpreted as a result of intraspecific facilitation at higher larval densities. UncrowdedB. formosensis had a shorter larval to pupal development and an earlier period of most rapid growth than uncrowdedH. ligurriens, suggesting the former may be superior in exploiting carcasses with limiting food.     

Reinforcement,stereotypy, and rule discovery

The effects of reinforced pretraining on subsequent rule discovery were examined with college students as subjects. Levels of behavioral stereotypy observed during reinforced and non-contingent pretraining were compared. During pretraining subjects received reinforcement if they pressed two keys in a particular sequence. During the problem session pressing each key four times was a necessary condition for reinforcement, but each problem had additional different requirements for reinforcement. Subjects were asked to solve the problems by discovering the rule that determined whether or not they received reinforcement. Levels of stereotyped responding during pretraining were equivalent for contingently and non-contingently trained subjects. During the problem session contingently pretrained, non-contingently pretrained, and naive subjects required equal numbers of trials to solve problems and solved the same number of problems. The results suggest that behavioral stereotypy observed in this experimental preparation may be due to repeated exposure to the task. Differences between the results observed in this study and that of Schwartz (1982) and implications for the use of reinforcement procedures in applied settings are discussed.

     

The Control Narrative of the Internet

This article examines how mediation and control operate in cyberspace through a control narrative, or actors' awareness and expectation that symbolic meanings may be monitored and used by diverse audiences for various purposes. A control narrative is implicated in numerous attempts and logics to monitor and regulate Internet use. The control narrative is more explicit as fear and control are reflexively joined to virtual communication. The focus is on recent developments in surveillance, deception, and entrapment in “Internet stings” by formal agents of social control in the name of protecting children from predators and pedophiles and U.S. citizens from terrorism. Several implications of the control narrative for communication are offered, along with questions for further research.