A solid ball placed on a rotating turntable is known to roll slowly around a circular path, at a speed 3.5 times slower than the turnable itself. If the ball is located in a straight track across a diameter of the turntable, then it accelerates rapidly to the edge. Both effects were filmed in slow motion using a video camera and a cake decoration…

Background: Coding has been added to school curricula in several countries, being one of the necessary competencies of the 21st century. Although it has also been suggested to foster the development of several cognitive skills such as computational thinking and problem-solving, studies on the effects of coding are very limited, provide mixed…

The field of special education has become increasingly interested in and concerned about the costs associated with delivering programs and services to students. Yet, to date, there has been relatively limited data on the costs or return on investment of special education services and preventive interventions. There is an opportunity to learn from…

Periodic changes in occupational classifications make it difficult to obtain consistent measures of social class over time, potentially jeopardizing research on class-based trends. The severity of this problem depends, in part, on the measurement strategies used to address those changes. The authors propose that when a sample has been coded partly…

Is there an optimal grading scheme? Do psychology instructors prefer one grading scheme over another? These questions were recently posted on the Society for the Teaching of Psychology Facebook page. After reading the responses, we realized that research in the domain of math cognition might help to shed light on an optimal grading scheme and put…

As part of its Partnership for Pre-K Improvement (PPI) initiative, the Bill & Melinda Gates Foundation sponsored the RAND Corporation to study the cost of high-quality pre-K programming. The RAND study included three states--Oregon, Tennessee, and Washington--that were partnering with the foundation under PPI. The objective of the study was to…

The synthetic control method (SCM) is a popular approach for estimating the impact of a treatment on a single unit in panel data settings. The "synthetic control" is a weighted average of control units that balances the treated unit's pre-treatment outcomes and other covariates as closely as possible. A critical feature of the original…

Background: When RCTs are not feasible and time series data are available, panel data methods can be used to estimate treatment effects on outcomes, by exploiting variation in policies and conditions over time and across locations. A complication with these methods, however, is that treatment timing often varies across the sample, for example, due…

Interaction forces between magnetic fields and current loops play a central role in the theory of magnetism. This work describes a reasonably simple and cheap experiment for demonstrating this issue: the force on a thin coil due to a nearby cylindrical magnet. The magnitude of the force as well as its attractive/repulsive character is comfortably…

An original approach using three appropriate Pythagorean triangles is presented for the detailed mathematical analysis of an ideal conical pendulum. The triangles that are used in this analysis relate specifically to the physical dimensions of the conical pendulum, the magnitudes of the forces acting during the conical pendulum motion and a…

Purpose: Anterior tongue shape during /s/ production is often described as "tip-up" or apical, versus "tipdown" or laminal. Typically, this is determined by observing the shape of the anterior midline tongue. The purpose of this study was to identify methods of curvature calculation that quantify the observed shape differences…

Item Response Theory (IRT) models traditionally assume a normal distribution for ability. Although normality is often a reasonable assumption for ability, it is rarely met for observed scores in educational and psychological measurement. Assumptions regarding ability distribution were previously shown to have an effect on IRT parameter estimation.…

Online platforms offer new opportunities to study human behavior. However, while social scientists are often interested in using behavioral trace data--data created by a user over the course of their everyday life--to draw inferences about users, many online platforms only allow data to be sampled based on user activities (leading to data sets…

Information quality deficiencies have been detected in occupational safety and health surveys in Europe, which typically gather self-reported data responded by employers or their representatives. For instance, their low response rates and informant profiles make estimations on establishments with safety representatives (SRs) unreliable. We tested…

Our objective is the estimation of voter transitions between two consecutive parliamentary elections. Usually, such analyses have been based either on individual survey data or on aggregated data. To move beyond these methods and their respective problems, we propose the application of so-called hybrid models, which combine aggregate and…