Outliers in educational achievement data: Their potential for the improvement of performance
Statistical outliers (Barnett and Lewis, 1994) have customarily been identified as either potential threats to data integrity (Cook, 1977) or as potential distortions of estimates of central tendency (Strutz, 2010). In both circumstances outliers are treated as having nuisance value. On the other hand, Gladwell (2008) views outliers as success stories. The study adopts the latter approach to reach to classrooms and teachers which add value in student’s academic capabilities. Scores of 86207 students from 423 government schools in 2010 middle school (Grade VI to VIII) promotion examinations are analysed to explore the possibility of identifying gifted teachers.
The study reports successful use of non-parametric methods of box plot and quartile formula to identify outstanding student performance. This performance is independent of overall school achievement, school size, student gender and is attributable to either individual or combined teaching effort.