The purpose of the South African Mathematics Olympiad is to generate interest in mathematics and to identify the most talented mathematical minds. Our focus is on how the handling of missing data affects the selection of the ‘best’ contestants. Two approaches handling missing data, applying the Rasch model, are described. The issue of guessing is investigated through a tailored analysis. We present two microanalyses to illustate how missing data may impact selection; the first investigates groups of contestants that may miss selection under particular conditions; the second focuses on two contestants each of whom answer 14 items correctly. This comparison raises questions about the proportion of correct to incorrect answers. Recommendations are made for future scoring of the test, which include reconsideration of negative marking and weighting as well as considering the inclusion of 150 or 200 contestants as opposed to 100 contestants for participation in the final round.

中文翻译：

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在奥运会类型测试中调查缺失数据的处理方法–南非数学奥林匹克竞赛中选择有效性的案例

南非数学奥林匹克竞赛的目的是引起人们对数学的兴趣，并确定最有才华的数学头脑。我们的重点是如何处理丢失的数据如何影响“最佳”参赛者的选择。描述了应用Rasch模型处理丢失数据的两种方法。猜测问题是通过量身定制的分析进行调查的。我们提供了两个微观分析，以说明缺失的数据如何影响选择。首先调查在特定条件下可能会错过选择的参赛者群体；第二个重点是两个参赛者，每个参赛者都能正确回答14个项目。这种比较提出了关于正确答案与错误答案比例的问题。提出了建议，以便将来对考试进行评分，