Evaluating SEM Model Fit with Small Degrees of Freedom

2021 ◽  
pp. 1-36
Author(s):  
Dexin Shi ◽  
Christine DiStefano ◽  
Alberto Maydeu-Olivares ◽  
Taehun Lee
Keyword(s):  
Degrees Of Freedom ◽  
Model Fit

scholarly journals Nuclear data adjustment using Bayesian inference, diagnostics for model fit and influence of model parameters

2020 ◽  
Vol 239 ◽  
pp. 13003
Author(s):  
D. Kumar ◽  
S. B. Alam ◽  
H. Sjöstrand ◽  
J.M. Palau ◽  
C. De Saint Jean
Keyword(s):  
Bayesian Inference ◽  
Degrees Of Freedom ◽  
Nuclear Data ◽  
Information Criteria ◽  
Least Square ◽  
Model Fit ◽  
Adjustment Process ◽  
Model Parameters ◽  
Test Case ◽  
Bayesian Approximation

The mathematical models used for nuclear data evaluations contain a large number of theoretical parameters that are usually uncertain. These parameters can be calibrated (or improved) by the information collected from integral/differential experiments. The Bayesian inference technique is used to utilize measurements for data assimilation. The Bayesian approximation is based on the least-square or Monte-Carlo approaches. In this process, the model parameters are optimized. In the adjustment process, it is essential to include the analysis related to the influence of model parameters on the adjusted data. In this work, some statistical indicators such as the concept of Cook’s distance; Akaike, Bayesian and deviance information criteria; effective degrees of freedom are developed within the CONRAD platform. Further, these indicators are applied to a test case of 155Gd to evaluate and compare the influence of resonance parameters.

scholarly journals What Makes a Humanitarian Crisis Severe and Can Severity be Quantified? Assessment of the Global Severity Crisis Index

2020 ◽  
Author(s):  
Velma K Lopez ◽  
Angeliki Nika ◽  
Curtis Blanton ◽  
Leisel Talley ◽  
Richard Garfield
Keyword(s):  
Factor Analysis ◽  
Degrees Of Freedom ◽  
Goodness Of Fit ◽  
Real Life ◽  
Severity Index ◽  
Factor Loading ◽  
Second Order ◽  
Model Fit ◽  
Latent Construct ◽  
Humanitarian Response

BackgroundHumanitarian response actors evaluate crisis severity with the INFORM Severity Index, a publicly available metric. This index, however, has not undergone critical statistical review. If imprecise or incorrect, humanitarian response may be negatively impacted.MethodsThe INFROM Severity Index is calculated from 35 publicly available indicators, which conceptually reflect the severity of each crisis We used 172 unique global crises from the INFORM SEVERITY Index database that occurred January 1 to November 30, 2019, or were ongoing by this date. We applied exploratory factor analysis (EFA) to determine common factors within the dataset. We then applied a second-order confirmatory factor analysis (CFA) to predict crisis severity as a latent construct. Model fit was assessed via chi-square goodness-of-fit statistic, Comparative Fit Index (CFI), Tucker-Lewis Index (TLI), and Root Mean Square Error of Approximation (RMSEA).ResultsThe EFA models suggested a 3- or 4-factor solution, with 46% and 53% variance explained in each model, respectively. The final CFA was parsimonious, containing three factors comprised of 11 indicators, with reasonable model fit (Chi-squared=107, with 40 degrees of freedom, CFI=0.94, TLI=0.92, RMSEA=0.10). In the second-order CFA, the magnitude of standardized factor-loading on the ‘societal governance’ latent construct had the strongest association with the latent construct of ‘crisis severity’ (0.73), followed by the ‘humanitarian access/safety’ construct (0.56). Conclusions: A metric of crisis-severity is a critical step towards improving humanitarian response, but only when it reflects real life conditions. Our work is a first step in refining an existing framework to quantify crisis severity.

scholarly journals Assessing the Suitability of The Adapted Scientific Epistemic Beliefs Questionnaire in Namibia

2019 ◽  
Vol 9 (2) ◽  
pp. 62
Author(s):  
Simson Ndadaleka Shaakumeni
Keyword(s):  
Degrees Of Freedom ◽  
Two Dimensions ◽  
Epistemic Beliefs ◽  
Model Fit ◽  
Chi Square ◽  
Good Reliability ◽  
Four Dimensions ◽  
Significant Difference ◽  
The Mean ◽  
Overall Reliability

This study adapted and validated a questionnaire for assessing Namibian students’ scientific epistemic beliefs and explore their relation to achievement in science, gender, grade and socioeconomic status. The study was correlational, with a sample of 944 (45% male; 55% female) Grades 11 and 12 students with the mean age M=17.9, SD= 1.4. A Likert scale questionnaire comprised of four dimensions of beliefs: source; certainty; development; and justification of scientific knowledge. The adapted questionnaire had good reliability with the Cronbach’s alpha of subscales ranging from .80 to .83 and the overall reliability of .70.  Model fit analysis yielded good statistical fit with Chi-square ratio to degrees of freedom= 2.71, RMSEA= 0.043, CFI= 0.95, TLI= 0.94, SRMR= .032. The overall regression model was significant F (4, 939) =8.218, p <.001, R2= .034. Two dimensions, certainty (b=.154, p<.001) and justification (b=.100, p<.05) statistically significantly predicted achievement in science. There was statistically significant difference in beliefs about source in terms of gender and grade and about certainty in terms of grade. The results show that the questionnaire works well with the Namibian sample used given the good model fit for the data and reliability. Results are discussed in terms of 21st century skills development.

scholarly journals Estructura De Las Percepciones De Riesgo En Torno A La Escasez Y El Desabasto De Agua Global Y Local

Xihmai ◽  
2013 ◽  
Vol 8 (15) ◽  
Author(s):  
Cruz Garcí­a Lirios ◽  
Javier Carreón Guillén ◽  
Juan Mecalco Ortiz ◽  
Jorge Hernández Valdés ◽  
Miguel Bautista Miranda ◽  
...  
Keyword(s):  
Internal Consistency ◽  
Water Availability ◽  
Perceived Risk ◽  
Degrees Of Freedom ◽  
Water Shortage ◽  
Model Fit ◽  
Factor Analyses ◽  
Perception Of Risk ◽  
Perceptual Factor ◽  
Scale Validity

Resumen   Los estudios psicológicos de la sustentabilidad hí­drica han demostrado que las situaciones especí­ficas de desabasto de agua influyen en las acciones de ahorro. Si el desabasto es percibido como temporal o momentáneo, la percepción de riesgo tiende a disminuir influyendo en la inacción de los usuarios del servicio de agua potable. En tal contexto, el objetivo del presente estudio fue construir un instrumento para medir las dimensiones de la percepción de riesgo frente a situaciones extremas de disponibilidad hí­drica. Para tal propósito, se revisaron los estudios perceptuales y se seleccionaron reactivos para su evaluación por jueces. La aplicación del instrumento se llevó a cabo con una muestra de 100 estudiantes. Los resultados muestran que la escala es confiable (alfa de .75) ya que es una  evidencia de consistencia interna entre los reactivos y la escala. La validez se estableció con pesos factoriales superiores a .300 entre los indicadores y el factor perceptual. Los análisis de covarianza entre los indicadores perceptuales muestran la incidencia de otros factores cognitivos y el modelo reflectivo indicó un ajuste entre las relaciones hipotéticas y las relaciones observadas (X2 = 17.645; 23 grados de libertad; p = .000). A partir de los hallazgos se infiere que la percepción de riesgos es multidimensional ya que la heterogeneidad de expectativas corresponde con la diversidad de riesgos en torno a la escasez y desabasto. Palabras claves: Escasez, Desabasto, Percepción, Riesgo y Multidimensionalidad Abstract   Psychological studies of water sustainability have shown that the specific situations of water shortage affecting saving actions. If the shortage is perceived as temporary or momentary perception of risk tends to decrease inaction influencing users' water service. In this context, the objective of this study was to construct an instrument to measure the dimensions of perceived risk from extremes of water availability. For this purpose, we reviewed and selected perceptual reagents for evaluation by judges. The application of the instrument was carried out on a sample of 100 students. The results show that the scale is reliable (alpha .75) as it is an evidence of internal consistency between the reactants and scale. Validity was established with factor loadings above .300 between indicators and the perceptual factor. Analyses of covariance between perceptual indicators show the incidence of cognitive and other factors indicated a reflective model fit between the hypothesized relationships and the relationships observed (X2 = 17 645, 23 degrees of freedom, p = .000). From the findings it appears that the perception of risk is multidimensional and that heterogeneity of expectations match the diversity of risks around scarcity and shortage. Keywords: Scarcity, shortage, Perception, Risk and Multidimensionality

scholarly journals Preadmission predictors of graduation success from a physical therapy education program in the United States

2019 ◽  
Vol 16 ◽  
pp. 5
Author(s):  
Gretchen Roman ◽  
Matthew Paul Buman
Keyword(s):  
Physical Therapy ◽  
Grade Point Average ◽  
Degrees Of Freedom ◽  
The United States ◽  
Model Fit ◽  
Physical Therapy Education ◽  
Graduate Record Examination ◽  
Grade Point ◽  
Graduation Success ◽  
Therapy Education

Purpose: The field of physical therapy education is seeking an evidence-based approach for admitting qualified applicants, as previous research has assessed various outcomes, impeding practical application. This study was conducted to identify preadmission criteria predictive of graduation success. Methods: Data from the 2013–2016 graduating cohorts (n=149) were collected. Predictors included verbal Graduate Record Examination rank percentile (VGRE%), quantitative GRE rank percentile, and analytical GRE rank percentile, the admissions interview, precumulative science grade point average (SGPA), precumulative grade point average (UGPA), and a reflective essay. The National Physical Therapy Examination (NPTE) and grade point average at the time of graduation (GGPA) were used as measures of graduation success. Two separate mixed-effects models determined the associations of preadmission predictors with NPTE performance and GGPA. Results: The NPTE model fit comparison showed significant results (degrees of freedom [df]=10, P=0.001), decreasing within-cohort variance by 59.5%. NPTE performance were associated with GGPA (β=125.21, P=0.001), and VGRE%, the interview, the essay, and GGPA (P≤0.001) impacted the model fit. The GGPA model fit comparison did not show significant results (df=8, P=0.56), decreasing within-cohort variance by 16.4%. The GGPA was associated with the interview (β=0.02, P=0.04) and UGPA (β=0.25, P=0.04), and VGRE%, the interview, UGPA, and the essay (P≤0.02) impacted model fit. Conclusion: In our findings, GGPA predicted NPTE performance, and the interview and UGPA predicted GGPA. Unlike past evidence, SGPA showed no predictive power. The essay and VGRE% warrant attention because of their influence on model fit. We recommend that admissions ranking matrices place a greater weight on the interview, UGPA, VGRE%, and essay.

scholarly journals On the Degrees of Freedom of Mixed Matrix Regression

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Pan Shang ◽  
Lingchen Kong
Keyword(s):  
Regression Model ◽  
Degrees Of Freedom ◽  
Modern Science ◽  
Model Fit ◽  
Vector Data ◽  
Mixed Matrix ◽  
Science Data ◽  
Adaptive Selection ◽  
Nuclear Norm Regularization ◽  
Consistent Property

With the increasing prominence of big data in modern science, data of interest are more complex and stochastic. To deal with the complex matrix and vector data, this paper focuses on the mixed matrix regression model. We mainly establish the degrees of freedom of the underlying stochastic model, which is one of the important topics to construct adaptive selection criteria for efficiently selecting the optimal model fit. Under some mild conditions, we prove that the degrees of freedom of mixed matrix regression model are the sum of the degrees of freedom of Lasso and regularized matrix regression. Moreover, we establish the degrees of freedom of nuclear-norm regularization multivariate regression. Furthermore, we prove that the estimates of the degrees of freedom of the underlying models process the consistent property.

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

Representing utility and deploying the body

2020 ◽  
Vol 43 ◽  
Author(s):  
David Spurrett
Keyword(s):  
Functional Activity ◽  
Degrees Of Freedom ◽  
The Body ◽  
Target Article ◽  
Processing Demands ◽  
The Many

Abstract Comprehensive accounts of resource-rational attempts to maximise utility shouldn't ignore the demands of constructing utility representations. This can be onerous when, as in humans, there are many rewarding modalities. Another thing best not ignored is the processing demands of making functional activity out of the many degrees of freedom of a body. The target article is almost silent on both.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

Das Experten-Novizen-Paradigma und die Vertrauenskrise in der Psychologie

2016 ◽  
Vol 23 (4) ◽  
pp. 131-140 ◽  
Author(s):  
Philip Furley ◽  
Karsten Schul ◽  
Daniel Memmert
Keyword(s):  
Degrees Of Freedom

Zusammenfassung. Das Ziel des vorliegenden Beitrages ist es anhand eines vielverwendeten Paradigmas in der Sportwissenschaft – dem Experten-Novizen-Vergleich – zu prüfen, ob die momentane Vertrauenskrise in der Psychologie ebenfalls die Sportpsychologie betreffen könnte. Anhand einer exemplarischen Studie zeigen wir, dass es innerhalb dieses Paradigmas zu kontroversen Befunden kommt, welche durch die vermuteten Ursachen der Vertrauenskrise (Researcher Degrees of Freedom, kleine Stichprobengrößen) erklärt sein könnten. Zusätzlich argumentieren wir, dass weitere Faktoren (Konfundierung, Stichprobengrößen, Rosenthal Effekt, Expertise-Definition) innerhalb dieses Paradigmas die Reproduzierbarkeit von Erkenntnissen in Frage stellen. Wir diskutieren mögliche Maßnahmen, wie die dargestellten Probleme des Experten-Novizen-Paradigmas in zukünftigen Forschungsarbeiten gelöst werden können.

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