Reliability and validity of the Math Essential Skill Screener?Elementary Version (MESS-E)

Abstract

The Math Essential Skill Screener–Elementary Version (MESS-E) is a screener devised to identify primary grade students at risk for math difficulties. Item analysis, interitem consistency, test–retest reliability, decision efficiency, and construct validity of the MESS-E were studied using four independent samples of boys and girls grades 1–3 (aged 6–8). Item analysis revealed median item difficulty of .64 and median item discrimination of .75. Interitem consistency was .92 (n = 171) and .94 (n = 711), while 30-day test–retest reliability was .86 (n = 125). Exploratory factor analysis indicated a one-factor solution accounting for 37% of observed variance. LISREL 7 confirmatory factor analysis procedures determined that the one-factor model fit the standardization sample data poorly (goodness-of-fit index = .729, χ2 to df ratio = 9.91). The MESS-E yielded concurrent validity coefficients (n = 171) of .74 with the Woodcock–Johnson: Tests of Achievement–Revised (WJ-R) Math Cluster, .80 with the Wide-Range Achievement Test–Revised (WRAT-R) Arithmetic subtest and .73 with the KeyMath-R Operations Area standard scores. A diagnostic efficiency study yielded a total predictive value (TPV) of .93, sensitivity = .98, specificity = .88, positive predictive power (PPP) = .89, negative predictive power (NPP) = .98, and incremental validity = 39%. The MESS-E displayed a slight tendency to overidentify children potentially at risk for math difficulties. © 1998 John Wiley & Sons, Inc.