Learning difficulties with median and quartiles concepts in the 8th grade students: formula versus plot comparative study

Abstract

Last three decades studies point out some difficulties when calculating and interpreting the median for different levels of study. Yet there is still no answer to what kind of association exists among those observed difficulties or even if there are any. The study was done with a set of 81 responses of the 8º grade students relative to four situation problems proposed. A documental analysis was realized on each response. The errors found within the calculus and interpretation of median and quantiles were identified and classified. Based on a quantitative approach and using Cramer’s V coefficient as statistical measure of association, the aim was to find out if there is a statistical association between the capacity of calculating the median and quartile values and the correct interpretation of those values after changes in data either concerning the calculated value or looking at the correspondent boxplot. The statistical analysis of the responses showed weak or moderate association in some cases; moreover, the analysis suggested that there is not association between the difficulties of calculating the median value and identifying the value in a boxplot after changing the data. This lack of association might indicate the distinct way students look at each form not realizing the existing relation as if they were two different issues.