There is a long-standing debate as to whether nonexperimental estimators of causal effects of social programs can overcome selection bias. Most existing reviews either are inconclusive or point to significant selection biases in nonexperimental studies. However, many of the reviews, the so-called "between-studies," do not make direct…

The performance of the normal theory bootstrap (NTB), the percentile bootstrap (PB), and the bias-corrected and accelerated (BCa) bootstrap confidence intervals (CIs) for coefficient omega was assessed through a Monte Carlo simulation under conditions not previously investigated. Of particular interests were nonnormal Likert-type and binary items.…

As a result of the use of random assignment to treatment, randomized experiments typically have high internal validity. However, units are very rarely randomly selected from a well-defined population of interest into an experiment; this results in low external validity. Under nonrandom sampling, this means that the estimate of the sample average…

Background: Research into specific illnesses and the development of new treatments may only become possible as new technologies become available. When used for research, such technologies may best be described as "intrusive", in that they require a considerable willingness and commitment on the part of the participants. This has…

The purpose of this research was to find the relation-ship between the predominant learning styles among university online students and their attitude toward online education. Data were collected from 385 students enrolled in undergraduate and graduate programs from four universities in the state of Nuevo Leon, Mexico. Significant effects of…

This article reports on an analysis of 320 empirical research articles published between 1993 and 2010 in three of the leading "childhood" journals. The study looked to establish the potential samples used in accounts of empirical research studies with children; and to explore the methodology employed. The first part of this article…

We present a proposal--"The Sampling Hypothesis"--suggesting that the variability in young children's responses may be part of a rational strategy for inductive inference. In particular, we argue that young learners may be randomly sampling from the set of possible hypotheses that explain the observed data, producing different hypotheses with…

This paper investigates four methods of linear equating under the common item nonequivalent groups design. Three of the methods are well known: Tucker, Angoff-Levine, and Congeneric-Levine. A fourth method is presented as a variant of the Congeneric-Levine method. Using simulation data generated from the three-parameter logistic IRT model we…

This supplement contains documentation on the explicit and implicit stratification variables included in the TIMSS 2011 data files. The explicit strata are smaller sampling frames, created from the national sampling frames, from which national samples of schools were drawn. The implicit strata are nested within the explicit strata, and were used…

This report summarizes the research activities and findings from the Teaching and Learning Research Initiative (TLRI)-funded project conducted in Year 13, introductory university and workplace classes, entitled "'Bootstrapping' Statistical Inferential Reasoning". The project was a 2-year collaboration among three statisticians, two…

The National Blindness Prevention Program in Mali has broadcast messages on the radio about trachoma as part of the country's trachoma elimination strategy since 2008. In 2011, a radio impact survey using multi-stage cluster sampling was conducted in the regions of Kayes and Segou to assess radio listening habits, coverage of the broadcasts,…

This study was conducted to reveal the perceptions of history, geography and social studies teachers giving the social studies lesson at primary schools in Turkey and Afghanistan towards the social studies lesson. The working group of the study involves history, geography and social studies teachers rendering service in Tokat and Kayseri provinces…

College student attrition rates remain constant despite institution level efforts. This retrospective archival study examined how individual instructors at the course level might impact academic success and retention by acting on a real time at risk warning system. Five semesters of scores on the first exam in an undergraduate psychology course…

The current study investigates how attitudes towards seeking psychological help relate to internal working models of attachment (self-model and other-model) and ruminative tendencies. The study includes 589 Turkish university students (278 females, 308 males and 3 unknown) by implementing a convenient sampling procedure. The average age of the…

Peer victimization appears heritable, but it is unclear whether the traits that confer genetic risk require time and familiarity with a perpetrator to manifest or whether novel and brief interactions can lead to received aggression that demonstrates similar genetic risk. We examined 20-minute, peer-play interactions between 5-year-olds, pairing…