Table 3.

The item development phases

Stage	Description	Output
Generation	Analyze the Indonesian mathematics curriculum, mathematics textbooks, and Indonesian national examination for mathematics	Curriculum goals, basic skills for statistics, typical statistical tasks, and statistical topics to be included
Selection	Analyze some potential items from different sources	14 selected items
Adjustment	Adapt and adopt the selected items	The adapted 14 items
Pilot interview I	Examine the clarity of the items and the cognitive processes of four students with average academic achievement	The revised 14 items
Pilot test	Trial the items with twelve (low- to high-achieving) students to determine test administration process, test duration, and to understand students' written responses	Test administration procedure, test duration, and sample of students’ written responses
Pilot interview II	Investigate the cognitive processes underlying the written responses of students on a pilot test to enhance the quality of an interview protocol	10 revised items with their interview protocol