Resumo

LEON GOMEZ, Nelly A. Difficulties and mistakes solving verbal problems on  bayes´s theorem: A Case with Future MathTeachers. Paradìgma [online]. 2008, vol.29, n.2, pp.187-219. ISSN 1011-2251.

As part of their academic training, math students from Universidad Pedagógica Experimental Libertador, Maturín, Venezuela, must approve a course in probability and inferential statistic (semester seven) According to previous research, this course is one of the most difficult in relation to understanding the theory and solving problems like Bayes’ theorem. Among other reasons, the difficulties are related to verbal expression, the amount of data and conditions involved. This is a qualitative interpretative case study with an orientation toward action in the classroom. The author is at the same time researcher and professor and her 20 students are subjects under study. The  purpose was to evaluate alternative  instructional strategies that have been successful in other contexts, centered in the use of a particular solving problem model, the use of different kind of objects such as frequencies, proportions, percentages and probabilities, and the use of different representation strategies like two way tables, tree  and  area diagrams. Results show that, even when it took longer time than expected, the goal was not achieved in term of students understanding of concepts and abilities for solving Bayes’ theorem problems. Their main restrictions were the identification of events and their probabilities, the use of the variety of representations and failures in reasoning about probability, such as the  bases-rate fallacy, time axis misconception and  the fallacy of the transpose conditional.

Palavras-chave : Bayes’ theorem; Problem solving; Conditional probability; Probability reasoning.