Validation of Scores/Measures from a K-2 Developmental Assessment in Mathematics

Abstract

This study describes psychometric investigations of a developmental assessment in mathematics composed of 19 performance tasks. Techniques from classical and the many-faceted Rasch approaches were combined to analyze field test data from a mixedage sample ( n = 110). Descriptive statistics on scores from the overall scale and subdomains indicated increased proficiency with age. Convergent validity coefficients of scores with scaled scores of the Stanford Achievement Test mathematics battery ranged from .22 to .57; internal consistency reliability of the total scores on proficiency and independence were .90 and .92, respectively; and median interrater reliability was .80. Classical item statistics and Rasch logit difficulties of tasks suggested an ordered scale structure, although eight tasks did not fit Rasch criteria. The original and calibrated task orderings were consistent at the extreme ends of the scale. Findings point to directions for future improvement of the scale and rater training programs.