There is such doubt in research practice about the reliability of difference scores that granting agencies, journal editors, reviewers, and committees of graduate students' theses have been known to deplore their use. This most maligned index can be used in studies of change, growth, or perhaps discrepancy between two measures taken on the same…

The purpose of this study was to investigate the factor structure, internal consistency, and reliability of the Readiness to Respond to Intervention Scale (RRIS), which is designed to assess adolescents' readiness to change. This measure is based on the Stage of Change Scale and assesses three stages of the Stage of Change Model (i.e.,…

This study systematically reviewed the validity, reliability, sensitivity to change, and clinical utility of measurements of participation for children with cerebral palsy. Sixteen measures were identified and seven met the inclusion criteria of having 30% content measuring participation, for use with children aged 5 to 13 years with physical…

It is recognized that the typical difference score used by educators is likely to be relatively weak in reliability. Formulas are developed for estimating changes in the reliability of X-Y under the assumption of equal or unequal variances before and after reliabilities are modified. (SLD)

The cognitive constructions coding system (CCCS) was designed for coding client's expressed problem constructions on four dimensions: intrapersonal-interpersonal, internal-external, responsible-not responsible, and linear-circular. This study introduces, and examines the reliability and validity of, a modified version of the CCCS--a version that…

The clarification provided by Williams and Zimmerman on the reliability of gain scores is translated into recognizable patterns of change that tend to produce reliable or unreliable gain scores. The relevance of the traditional idea of reliability to the measurement of change is also discussed. (SLD)

Modified equations for the validity and reliability of difference scores that describe applied testing situations are examined. This examination reveals that simple gain scores can be more useful in research than has commonly been believed. Simple gain scores are neither inherently unreliable nor lack predictive validity. (SLD)

The superiority of multiwave designs over two-wave designs in the measurement of individual growth and change is explored by examining the increase in reliability afforded by collecting additional waves of data. Results are discussed in terms of the impact on longitudinal studies of individual change. (SLD)

The reliability of a gain is determined by the reliabilities of the components, the correlation between them, and their standard deviations. Reliability is not inherently low, but the components of gains in many investigations make low reliability likely and require caution in the use of gain scores. (SLD)

The critiques by L. Collins and L. Humphreys in this issue illustrate problems with the use of gain scores. Collins' examples show that familiar formulas for the reliability of differences do not reflect the precision of measures of change. Additional examples demonstrate flaws in the conventional approach to reliability. (SLD)

The growth curve approach to the measurement of gain of D. Rogosa, D. Brandt, and M. Zimowski (1982) was more fully developed by J. B. Willet and D. Rogosa (1985). Willet later (1989) discussed some practical aspects of applying a linear growth model and reached the conclusion that reliability may not always be a useful index for the measurement…

The reliability of the growth rate parameter estimate of Willet for a linear growth model is derived and examined critically. The effects on the reliability of the growth rate of intervals between longitudinal measurements and the covariances between longitudinal measurements are distinguished. (SLD)

Explanations for an observed change in Rasch item parameters ("b" values) from consecutive administrations of a professional licensing examination were investigated. Analysis of covariance indicated that the change was not related to item position or type. It is hypothesized that the change is attributable to shifts in curriculum…

By the spring of 2000, forty states had begun using student test scores to rate school performance. Twenty states have gone a step further and are attaching explicit monetary rewards or sanctions to a school's test performance. In this paper, the authors focus on accountability programs in which states measure the effectiveness of individual…

The Scholastic Aptitude Test (SAT) has been designed to test developed verbal and mathematics reasoning abilities of college-bound students, primarily high school juniors and seniors. For almost a decade there has been a research and development process to evaluate and change the entire SAT program. These changes were implemented in the SAT I:…