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2,726 results on '"Liu, Ren"'

1. Using Diagnostic Classification Models in Psychological Rating Scales

Author

Liu, Ren and Shi, Dexin

Subjects
diagnostic classification model, psychological rating scales, item response theory, classical test theory, Psychology, BF1-990
Abstract

The purpose of this article is to demonstrate how to use diagnostic classification models (DCMs) in psychological rating scales and reflect on how DCMs differ from classical test theory (CTT) and item response theory (IRT) scoring approaches in terms of assumptions and results. DCMs, a viral topic in today\IeC {\textquoteright }s psychometric world, has thrived in educational assessment. However, many researchers and practitioners are uncertain how DCMs could be used in psychological rating scales and what information they could provide. This article presents an example of applying CTT, IRT, and DCM scoring approaches with data from 10,000 respondents on an operational personality rating scale.

Published
2020
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11. Development and Validation of a Formative Evaluation Instrument for College Teaching

Author

Liu, Ren, Liu, Xiufeng, and Hutson, Lara

Abstract

This study aims to provide preliminary validation for a newly designed instrument to evaluate teaching effectiveness through student classroom engagement and learning gains. The instrument is titled the Middle Semester Classroom Survey of Student Engagement and Learning (MS-CSSEL); it consists of 31items to measure student classroom engagement in three dimensions and 19 items to measure student learning gains in three dimensions. To validate the instrument, 634 undergraduate students in a four-year research university participated in this study. The multidimensional Rasch model was used to conduct the analysis. The findings indicated that (a) items displayed a good fit to the Rasch model; (b) dimensions were distinct from each other; and (c) the items displayed high reliability. This instrument measures teaching effectiveness in a new perspective and provides college teachers with a new tool to gauge student engagement and learning gains for conducting evidence-based teaching improvement.

Published
2022

14. The NEAT Equating via Chaining Random Forests in the Context of Small Sample Sizes: A Machine-Learning Method

Author

Jiang, Zhehan, Han, Yuting, Xu, Lingling, Shi, Dexin, Liu, Ren, Ouyang, Jinying, and Cai, Fen

Abstract

The part of responses that is absent in the nonequivalent groups with anchor test (NEAT) design can be managed to a planned missing scenario. In the context of small sample sizes, we present a machine learning (ML)-based imputation technique called chaining random forests (CRF) to perform equating tasks within the NEAT design. Specifically, seven CRF-based imputation equating methods are proposed based on different data augmentation methods. The equating performance of the proposed methods is examined through a simulation study. Five factors are considered: (a) test length (20, 30, 40, 50), (b) sample size per test form (50 versus 100), (c) ratio of common/anchor items (0.2 versus 0.3), and (d) equivalent versus nonequivalent groups taking the two forms (no mean difference versus a mean difference of 0.5), and (e) three different types of anchors (random, easy, and hard), resulting in 96 conditions. In addition, five traditional equating methods, (1) Tucker method; (2) Levine observed score method; (3) equipercentile equating method; (4) circle-arc method; and (5) concurrent calibration based on Rasch model, were also considered, plus seven CRF-based imputation equating methods for a total of 12 methods in this study. The findings suggest that benefiting from the advantages of ML techniques, CRF-based methods that incorporate the equating result of the Tucker method, such as IMP_total_Tucker, IMP_pair_Tucker, and IMP_Tucker_cirlce methods, can yield more robust and trustable estimates for the "missingness" in an equating task and therefore result in more accurate equated scores than other counterparts in short-length tests with small samples.

Published
2023
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23. 3D spatiotemporally scalable in vivo neural probes based on fluorinated elastomers

Author

Le Floch, Paul, Zhao, Siyuan, Liu, Ren, Molinari, Nicola, Medina, Eder, Shen, Hao, Wang, Zheliang, Kim, Junsoo, Sheng, Hao, Partarrieu, Sebastian, Wang, Wenbo, Sessler, Chanan, Zhang, Guogao, Park, Hyunsu, Gong, Xian, Spencer, Andrew, Lee, Jongha, Ye, Tianyang, Tang, Xin, Wang, Xiao, Bertoldi, Katia, Lu, Nanshu, Kozinsky, Boris, Suo, Zhigang, and Liu, Jia

Published
2024
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47. Designing biocompatible functional hydrogels : experiments and simulations

Author

Liu, Ren, Eiser, Erika, and Lee, Alpha

Subjects
hydrogel, self-assembly, triblock copolymer, DNA
Abstract

Biocompatible functional hydrogels are ideal materials for future diagnostic sensors. Their responsiveness to external stimuli, often in the form of varying optical and mechanical properties, has greatly promoted the development in biosensing systems. In this thesis, I designed a hybrid hydrogel system using biocompatible triblock copolymers, also known as Pluronics, which have been functionalized with azide and azide-single-stranded (ss)DNA linkers. Here the azide group served as reaction agent to bind ssDNA covalently to the Pluronics' chain ends. The Pluronics used are known as F108 and F127, both having the same block-size ratio but differing in molecular weight. In depth experimental characterisation and computational simulation for these systems are presented in this thesis. First, I will present the experimental characterisation of the micellization and aggregation behaviour of azide and azide-ssDNA functionalized Pluronic F108, in dilute and semi-concentrated aqueous solutions; these results are also compared with their non-functionalized counterparts. I observed remarkable differences in the structural properties of those F108 samples, mainly due to the azide-functionalization which introduces non-specific hydrophobic interactions between the solvated PEO chain-ends of the Pluronics and thus promotes the formation of flower micelles. Next, I will discuss the structure of the various phases, presenting detailed Small-Angle X-Ray Scattering measurements. To understand the effect of the DNA on the phase behaviour of our systems, I will also present simulation data, which enabled us to explore the entire phase diagram for the plain and the ssDNA functionalized F108 in aqueous solution. In this simulation study, I also explored Pluronic F127 solutions, as these are used in many biological and bio-technological applications. By controlling the interplay between these two species, a fine control over the rheological, temperature-dependent response of these systems were obtained. The biocompatibility and thermo-reversibility of these materials opens the possibility for a large number of applications related to biomedicine and drug delivery fields in which a fine control of mechanical properties is usually required.

Published
2022
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