An analysis of some aspects of the role and performance of an "O"-level biology examination as an instrument for curriculum evaluation : a case study of the 1983 "O"-level biology examinations in Tanzania
An analysis of the Tanzanian O-level biology curriculum and the 1983 O-level biology examinations has been carried out in order to identify problem areas. The topics on which candidates performed worst were also among the topics that candidates and their teachers perceived as being difficult. Item analysis showed a wide variation 1n the facility and discrimination indices across the items of the Theory and Practical examinations. Topic facility indices and ability facility indices were low. The estimates of internal consistency reliability revealed that the reliabilities of both the Theory and Practical examinations were within acceptable ranges. Importance of objectives as both course objectives and examination objectives was studied, and the abilities concerned with scientific method were accorded highest priority by both teachers and panel members responsible for the general oversight of the curriculum and examinations. The classification of the questions according to the ability areas and topic areas tested by the examinations showed that all the ability areas and topic areas were examined, although to differing degrees. The priority listing of the aims of Practical examinations in biology in Tanzania were similar to priority listings of practical aims reported elsewhere. By factor analysis, it was revealed that the constructs underlying performance were related both to topic areas dealt with by the items, and to curriculum objectives tested. Some evidence was found that a 'Theoretical' mode of performance, a 'Practical' mode of performance, and a 'Continuous assessment' mode of performance constituted separate constructs. A comparison of the performance by different sexes in the different ability areas tested by the examinations showed an overall girls' superiority. There was no indication of sex superiority with regard to performance in the different topic areas tested; or in performance in Continuous assessment. Both sexes performed better in Continuous assessment than in the Final examination. Overall, the examinations seem to have been more suited for the selection of the candidates for entry into the limited places in higher educational institutions and for selected careers placement, than for evaluating the effectiveness of the course.