Individual differences in decision-making and confidence: capturing decision tendencies in a fictitious medical test

Decision-making is a complex process that is largely studied from an experimental perspective or in specific organizational contexts. As such, no generalizable framework exists with which to study decision-making from an individual differences perspective for predictive/selection purposes. By generalising a context-specific decision model proposed by Koriat and Goldsmith (1996), the focus of this research was to therefore test a novel framework for studying individual differences in decision-making tendencies. Utilising this framework within a fictitious Medical Decision-Making Test (MDMT) yielded five novel variables that provided unique insight into individuals’ decision tendencies: Optimal, Realistic, Incompetent, Hesitant and Congruent. Metacognitive confidence and its calibration (bias and CAQ) were used as predictor variables to validate this framework. One hundred ninety-three undergraduate students completed the MDMT and three cognitive ability tests with confidence ratings, a personality questionnaire, and the Need for Closure questionnaire. All decision tendency variables demonstrated excellent internal consistency and were predicted by the metacognitive variables incrementally to the remaining variables as hypothesized. Additionally, the metacognitive indices were found to generalize across the decision-making and cognitive tests. The results imply that this novel framework and MDMT reliably capture individuals’ decision behaviour that shares a meaningful relationship with their general confidence and calibration.     

The industrial lot and its sampling implications

It is shown that wrong inferences are drawn from samples because of failure to understand what constitutes a lot and because of failure to verify the existence of a lot in the practically useful sense. Time-tried methods of making valid inferences from samples without increased cost are pointed out.     

Intensity of parasitic infestation in silver carp, Hypophthalmichthys molitrix

Silver carp, Hypopthalmichthys molitrix is one of the most economically valuable fish species in Bangladesh. However, its production is often hindered by parasite-induced mortality. The present study reports the intensity of parasitic infestation in 216 specimens of H. molitrix collected from different fish markets in Rajshahi City, Bangladesh. Nine different parasite species (Trichodina pediculatus, Dactylogyrus vastator, Ichthyophthirius multifilis, Gyrodactylus elegans, Lernaea sp., Apiosoma sp., Myxobolus rohitae, Camallanus ophiocephali, and Pallisentis ophiocephali) were recovered from the gill, skin, stomach, and intestine of host fish. The highest level of infection was observed for host skin, while lower levels were observed for host gill, stomach, and intestine. The results also revealed that the intensity of parasite infection in different organs of H. molitrix varied with the season. In particular, the highest levels of infection were recorded during the winter period (November-February), when fish are most susceptible to parasites. The findings of the study will help in the management and conservation of H. molitrix.