In this paper, principal components methodology is used to derive simplified and cost effective indexes of water poverty. Using a well known data set for 147 countries from which an earlier five-component water poverty index comprising of "Resources," "Access," "Capacity," "Use" and "Environment" was constructed, we find that a simplified…

In this article the authors focus on the issue of the nonuniqueness of the maximum likelihood (ML) estimator of proficiency level in item response theory (with special attention to logistic models). The usual maximum a posteriori (MAP) method offers a good alternative within that framework; however, this article highlights some drawbacks of its…

The purpose of this study was to replicate and extend a previous study by Burns ("Education and Treatment of Children" 28: 237-249, 2005) examining the effectiveness of incremental rehearsal on computation performance. A multiple-probe design across multiplication problem sets was employed for one participant to examine digits correct per minute…

An A-B single-case design assessed at-risk students' responsiveness to mathematics interventions. Four culturally and linguistically diverse second-grade students were given a Tier 2 standard protocol mathematics intervention that included number sense instruction, modeling procedures, guided math drill and practice of addition and subtraction…

This study investigated whether students with reading disabilities (RD) showed greater regression in reading skills than did non-RD students over the summer vacation. The RD group consisted of 30 students in grades 4 to 6 from a private school for students with learning disabilities and a comparison group of 30 average readers in grades 4 to 6…

Explanations of the marked individual differences in elementary school mathematical achievement and mathematical learning disability (MLD or dyscalculia) have involved domain-general factors (working memory, reasoning, processing speed, and oral language) and numerical factors that include single-digit processing efficiency and multidigit skills…

In most school achievement research, the relationships between achievement and explanatory variables follow the Newton and Einstein concept/principle and the viewpoint of the macro-observer: Deterministic measures based on the mean value of a sufficiently large number of schools. What if the relationships between achievement and explanatory…

Randomized controlled trials (RCTs) are widely considered to be the gold standard in evaluating the impacts of a social program. When an RCT is infeasible, researchers often estimate program impacts by comparing outcomes of program participants with those of a nonexperimental comparison group, adjusting for observable differences between the two…

Computational thinking aims to outline fundamental skills from computer science that everyone should learn. As currently defined, with help from the National Science Foundation (NSF), these skills include problem formulation, logically organizing data, automating solutions through algorithmic thinking, and representing data through abstraction.…

For at least 2000 years people have been trying to calculate the value of [pi], the ratio of the circumference to the diameter of a circle. People know that [pi] is an irrational number; its decimal representation goes on forever. Early methods were geometric, involving the use of inscribed and circumscribed polygons of a circle. However, real…

This study gives an insight into the differences between student understanding of line graph slope in the context of physics (kinematics) and mathematics. Two pairs of parallel physics and mathematics questions that involved estimation and interpretation of line graph slope were constructed and administered to 114 Croatian second year high school…

For skills that involve hitting a target, subsequent judgments of target size correlate with prior success in hitting that target. We used an archery context to examine the judgment-success relationship with varied target sizes in the absence of explicit knowledge of results. Competitive archers shot at targets 50 m away that varied in size among…

The ability of nonexperimental estimators to match impact estimates derived from random assignment is examined using data from the evaluation of two interdistrict magnet schools. As in previous within-study comparisons, nonexperimental estimates differ from estimates based on random assignment when nonexperimental estimators are implemented…

In administration of individually administered intelligence tests, items are commonly presented in a sequence of increasing difficulty, and test administration is terminated after a predetermined number of incorrect answers. This practice produces stochastically censored data, a form of nonignorable missing data. By manipulating four factors…

A technique for automatic error analysis using interval mathematics is introduced. A comparison to standard error propagation methods shows that in cases involving complicated formulas, the interval approach gives comparable error estimates with much less effort. Several examples are considered, and numerical errors are computed using the INTLAB…