scholarly journals Science Abstract Model Simulation Framework

2021 ◽  
Author(s):  
Amir Masoud Abdol ◽  
Jelte M. Wicherts
Keyword(s):  
Publication Bias ◽  
Degrees Of Freedom ◽  
Model Simulation ◽  
Abstract Model ◽  
Simulation Framework ◽  
Questionable Research Practices ◽  
Quantitative Studies ◽  
Significance Levels ◽  
Study Designs ◽  
Modular Modelling

Meta-researchers increasingly study biases in quantitative study outcomes (effect sizes) that emerge from questionable research practices (QRPs) in designing, running, analyzing, and reporting studies. Here, we introduce an extensible and modular C++ simulation framework called SAM (Science Abstract Model) that enables systematic study of the effects of QRPs and researchers’ degrees of freedom (p-hacking) on a host of outcomes across the different phases of quantitative studies that test hypotheses. SAM achieves this by modular modelling of different entities and processes involved in research, from study designs and inferential criteria, the data collection and analyses, to the submission and acceptance of manuscripts in a journal. We demonstrate the advantages of our approach by reproducing and extending the Bakker, van Dijk, and Wicherts (2012) simulation study that investigated the effects of various p-hacking methods and publication bias on meta-analytic outcomes. We showcase how SAM’s modularity and flexibility makes it possible to easily examine the original study by modifying, adding, or removing different components— e.g., publication bias, different significance levels, or meta-analytic metrics. We focus our illustration on the fundamental question of whether lowering alpha will reduce the biases in the scientific literature.

How to Detect Publication Bias in Psychological Research

2019 ◽  
Vol 227 (4) ◽  
pp. 261-279 ◽  
Author(s):  
Frank Renkewitz ◽  
Melanie Keiner
Keyword(s):  
Publication Bias ◽  
Effect Size ◽  
Statistical Power ◽  
Type I Error ◽  
Psychological Research ◽  
Type I ◽  
True Effect Size ◽  
Questionable Research Practices ◽  
True Effect ◽  
Meta Analyses

Abstract. Publication biases and questionable research practices are assumed to be two of the main causes of low replication rates. Both of these problems lead to severely inflated effect size estimates in meta-analyses. Methodologists have proposed a number of statistical tools to detect such bias in meta-analytic results. We present an evaluation of the performance of six of these tools. To assess the Type I error rate and the statistical power of these methods, we simulated a large variety of literatures that differed with regard to true effect size, heterogeneity, number of available primary studies, and sample sizes of these primary studies; furthermore, simulated studies were subjected to different degrees of publication bias. Our results show that across all simulated conditions, no method consistently outperformed the others. Additionally, all methods performed poorly when true effect sizes were heterogeneous or primary studies had a small chance of being published, irrespective of their results. This suggests that in many actual meta-analyses in psychology, bias will remain undiscovered no matter which detection method is used.

scholarly journals Excess success in “Don’t count calorie labeling out: Calorie counts on the left side of menu items lead to lower calorie food choices”

2019 ◽  
Author(s):  
Gregory Francis ◽  
Evelina Thunell
Keyword(s):  
Success Rate ◽  
Publication Bias ◽  
Food Choices ◽  
Effect Sizes ◽  
Sample Sizes ◽  
Research Practices ◽  
Policy Makers ◽  
Questionable Research Practices ◽  
Calorie Labeling

Based on findings from six experiments, Dallas, Liu & Ubel (2019) concluded that placing calorie labels to the left of menu items influences consumers to choose lower calorie food options. Contrary to previously reported findings, they suggested that calorie labels do influence food choices, but only when placed to the left because they are in this case read first. If true, these findings have important implications for the design of menus and may help address the obesity pandemic. However, an analysis of the reported results indicates that they seem too good to be true. We show that if the effect sizes in Dallas et al. (2019) are representative of the populations, a replication of the six studies (with the same sample sizes) has a probability of only 0.014 of producing uniformly significant outcomes. Such a low success rate suggests that the original findings might be the result of questionable research practices or publication bias. We therefore caution readers and policy makers to be skeptical about the results and conclusions reported by Dallas et al. (2019).

scholarly journals Complex Bogie Modeling Incorporating Advanced Friction Wedge Components

2009 ◽  
Author(s):  
Brian Sperry ◽  
Corina Sandu ◽  
Brent Ballew
Keyword(s):  
Dynamic Behavior ◽  
Degrees Of Freedom ◽  
Model Simulation ◽  
Surface Friction ◽  
Rigid Bodies ◽  
Operating Conditions ◽  
Normal Operation ◽  
Contact Points ◽  
Modeling Software ◽  
Simulation Results

This research focuses on the dynamic behavior of the three-piece bogie that supports the freight train car bodies. While the system is relatively simple, in that there are very few parts involved, the behavior of the bogie is somewhat more complex. Our research focuses primarily on the behavior of the friction wedges under different operating conditions that are seen under normal operation. The Railway Technologies Laboratory (RTL) at Virginia Tech has been developing a model to better capture the dynamic behavior of friction wedges using 3-D modeling software. In previous years, a quarter-truck model, and half-truck variably damped model have been developed using MathWorks MATLAB®. This year, research has focused on the development of a half-truck variably damped model with a new (curved surface) friction wedge, and a half-truck constantly damped model, both using the MATLAB® based software program. Currently a full-truck variably damped model has been created using LMS Virtual.Lab. This software allows for a model that is more easily created and modified, as well as allowing for a much shorter simulation time, which became a necessity as more contact points, and more complex inputs were needed to increase the accuracy of the simulation results. The new model consists of seven rigid bodies: the bolster, two sideframes, and four wedges. We have also implemented full spring nests on each sideframe, where in previous models equivalent spring forces were used. The model allows six degrees-of-freedom for the wedges and bolster: lateral, longitudinal, and vertical translations, as well as pitch, roll, and yaw. The sideframes are constrained to two degrees-of-freedom: vertical and longitudinal translations. The inputs to the model are vertical and longitudinal translations or forces on the sideframes, which can be set completely independent of each other. The model simulation results have been compared with results from NUCARS®, an industrially-used train modeling software developed by the Transportation Technology Center, Inc. (TTCI), a wholly owned subsidiary of the Association of American Railroads (AAR), for similar inputs, as well as experimental data from warping tests performed at TTCI.

Multibody Modeling and Simulation of Monocopter Micro Air Vehicle

2015 ◽  
Vol 772 ◽  
pp. 401-409
Author(s):  
Mehrdad Ebrahimi Dormiyani ◽  
Afshin Banazadeh ◽  
Fariborz Saghafi
Keyword(s):  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Model Simulation ◽  
Static Stability ◽  
Flight Simulation ◽  
Control Surface ◽  
Free Flight ◽  
Nonlinear Simulation ◽  
Multibody Model ◽  
Air Vehicle

In the current paper, seven degrees of freedom multibody model of a monocopter air vehicle is developed based on the Newton-Euler approach along with nonlinear simulation in different flight phases. Aerodynamic forces and moments are modeled using blade element momentum theory. The sole control surface is modeled like a conventional flap on a wing. Free flight simulation is performed in MATLAB Simulink environment to evaluate the behavior of the system and to demonstrate the effectiveness and applicability of the proposed model. Simulation results show harmonic oscillations in Euler angles, linear and angular velocities that are consistent with the physics and mathematical foundations. Static stability of the vehicle is evident in free flight by careful choice of initial conditions. The presented multibody model is useful for comparative study and design purposes.

Application of joint error maximum mutual compensation for hexapod robots

Robotica ◽  
2008 ◽  
Vol 26 (1) ◽  
pp. 63-73
Author(s):  
Yauheni Veryha ◽  
Henrik Gordon Petersen
Keyword(s):  
Model Simulation ◽  
Good Practice ◽  
Industrial Robots ◽  
Simulation Framework ◽  
Positioning Accuracy ◽  
Mutual Compensation ◽  
End Effector ◽  
Infinity Norm ◽  
Hexapod Robots ◽  
Jacobian Inverse

SUMMARYA good practice to ensure high-positioning accuracy in industrial robots is to use joint error maximum mutual compensation (JEMMC). This paper presents an application of JEMMC for positioning of hexapod robots to improve end-effector positioning accuracy. We developed an algorithm and simulation framework in MatLab to find optimal hexapod configurations with JEMMC. Based on a real hexapod model, simulation results of the proposed approach are presented. Optimal hexapod configurations were found using the local minimum of the infinity norm of hexapod Jacobian inverse. JEMMC usage in hexapod robots can improve hexapod end-effector positioning accuracy by two times and more.

scholarly journals Prevalence of the Different Types of Palmar Creases Among Medical and Dental Students in Addis Ababa, Ethiopia

1970 ◽  
Vol 29 (3) ◽  
Author(s):  
Mekbeb Afework
Keyword(s):  
Addis Ababa ◽  
Dental Students ◽  
Normal Variants ◽  
Exact Test ◽  
Qualitative And Quantitative ◽  
Quantitative Studies ◽  
Different Types ◽  
Significance Levels ◽  
Medical And Dental Students ◽  
Apparently Healthy

BACKGROUND: Studies have suggested that identification of aberrant palmar creases may give clues for an early and noninvasive method of diagnosis of certain disease conditions. Toward this purpose, awareness of the normal variants of palmar creases must be first recognized. Accordingly, this study aimed to investigate the patterns of palmar creases in healthy Ethiopian population among Medical and Dental Students in Addis Ababa.SUBJECTS AND METHODS: Right and left palm pictures from 318 (177 females and 141 males) participants were taken using a mobile camera, and evaluated qualitatively. Observations were analyzed by Fisher's exact test, and significance levels for comparisons were set at p<0.05.RESULTS: Aberrant creases were observed in 13.8% of the palms. Simian crease was the most common among the aberrant crease types, followed by Suwon and Sydney. Palmar creases with two and three points of origin were significantly more common, respectively, in males and the females. Minor variants as accessory to the radial longitudinal crease and middle longitudinal crease were also observed.CONCLUSION: This study suggests that aberrant crease types at the observed frequencies may not be indicative of known disease conditions as they occurred in apparently healthy Ethiopians. However, the results of this study, besides revealing the patterns of palmar creases among Ethiopians, could give a baseline for studies aimed at diagnosis of disease conditions based on palmar crease configurations. Further qualitative and quantitative studies of palmar creases in wider populations with various conditions, including ethno-geographic factors, are recommended.

scholarly journals Using Emphasis-Purposeful Sampling-Phenomenon of Interest–Context (EPPiC) Framework to Reflect on Two Qualitative Research Designs and Questions: A Reflective Process

2019 ◽  
Author(s):  
Michael Kalu
Keyword(s):  
Qualitative Research ◽  
Research Question ◽  
Qualitative Inquiry ◽  
Reflective Process ◽  
Qualitative Research Design ◽  
Quantitative Studies ◽  
Purposeful Sampling ◽  
Research Designs ◽  
Research Questions ◽  
Study Designs

A satisfactory research question often signifies the beginning point for many researchers. While this can be true for quantitative studies because of pre-defined research questions, qualitative research questions undergo series of revisions through a reflective process. This reflective process provides the framework for the subjectivity associated with qualitative inquiry. The continuous iterative reflective process is an essential component for developing qualitative research questions that correspond with the various qualitative study designs. Although qualitative inquiry is term exclusively subjective, there is a need to use a framework in developing qualitative research questions. The Emphasis- Purposeful sampling- Phenomenon of interest – Context (EPPiC) framework guides qualitative researchers in developing and revising qualitative research questions to suit a specific qualitative approach. This article addresses both the development of a research question using the “EPPiC framework” and demonstrate how to revise the “developed” research question to reflect two qualitative research design. I developed a qualitative research question for Sally Thorne’s Interpretive Description design using the EPPiC Framework and subsequently revised the research question to suit a grounded theory design.

Influence Coefficients and Singularity Analysis of a Novel 3-UPU Parallel Mechanism

2017 ◽  
Author(s):  
Ziming Chen ◽  
Dongliang Cheng ◽  
Yang Zhang ◽  
Zhiwei Yang ◽  
Jin Zhou
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Model Simulation ◽  
Hessian Matrix ◽  
Symmetry Plane ◽  
Coefficient Matrix ◽  
Singularity Analysis ◽  
Influence Coefficient ◽  
Parasitic Motion ◽  
Moving Platform

A novel 3-UPU parallel mechanism with two rotational and one translational (2R1T) degrees of freedom (DOFs) is analyzed in this paper. The base and moving platform of this mechanism are always symmetric about a middle symmetry plane. The moving platform can rotate continuously about any axis on the middle symmetry plane, so there exists no parasitic motion during the rotation. Using the kinematic influence coefficient theory and the imaginary mechanism method, the first and second order influence coefficient matrix (namely Jacobian matrix and Hessian matrix) of this mechanism are derived. The relations between the velocity and acceleration of the moving platform and the actuated links are obtained. In order to verify the correctness of the theory, two numerical examples are enumerated and varified by the 3D model simulation. The singularities of this mechanism is discussed and the singular configurations of the mechanism, including one kind of limb singularity and two kinds of platform singularities, are obtained.

scholarly journals A modern method of multiple working hypotheses to improve inference in ecology

2020 ◽  
Vol 7 (6) ◽  
pp. 200231 ◽  
Author(s):  
Scott W. Yanco ◽  
Andrew McDevitt ◽  
Clive N. Trueman ◽  
Laurel Hartley ◽  
Michael B. Wunder
Keyword(s):  
Data Collection ◽  
Low Power ◽  
Null Hypothesis ◽  
Effective Means ◽  
Modern Method ◽  
Significance Testing ◽  
Null Hypothesis Significance Testing ◽  
Questionable Research Practices ◽  
Study Designs ◽  
Working Hypotheses

Science provides a method to learn about the relationships between observed patterns and the processes that generate them. However, inference can be confounded when an observed pattern cannot be clearly and wholly attributed to a hypothesized process. Over-reliance on traditional single-hypothesis methods (i.e. null hypothesis significance testing) has resulted in replication crises in several disciplines, and ecology exhibits features common to these fields (e.g. low-power study designs, questionable research practices, etc.). Considering multiple working hypotheses in combination with pre-data collection modelling can be an effective means to mitigate many of these problems. We present a framework for explicitly modelling systems in which relevant processes are commonly omitted, overlooked or not considered and provide a formal workflow for a pre-data collection analysis of multiple candidate hypotheses. We advocate for and suggest ways that pre-data collection modelling can be combined with consideration of multiple working hypotheses to improve the efficiency and accuracy of research in ecology.

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