Students’ Reasoning about Variability When Comparing Two Sets of Data from the Perspective of Commognitive

This study aims to explore students’ reasoning about variability when they compare two groups of data from the perspective of commognitive. The task contains two questions, namely comparing the distribution of the patient’s recovery time in the two treatments and choosing one of the two treatments that the patient should use. Data on the assignment were given in the form of ogive graphs. Interviews were conducted to get in-depth information about students’ reasoning on variability. Fifty-nine mathematics education students were involved in this study (16 male and 43 female). The students have studied material about measures of dispersion. Eight of them were chosen as the subjects of the study. The assignment was given to the students to be completed by thinking aloud. Data on the assignment were given in the form of ogive graphs. The finding of this study was that there are four categories of students' reasoning when they interpret variability, namely quantitative, confirmation, single center point, and informal categories. The educators can introduce students to various types of data displays that can foster the development of students' reasoning about variability. Further research can be carried out by assessing students' reasoning about the variability of various levels of education.