QSAR Assessing the Efficiency of Antioxidants in the Termination of Radical-Chain Oxidation Processes of Organic Compounds

Using the GUSAR 2013 program, the quantitative structure–antioxidant activity relationship has been studied for 74 phenols, aminophenols, aromatic amines and uracils having lgk7 = 0.01–6.65 (where k7 is the rate constant for the reaction of antioxidants with peroxyl radicals generated upon oxidation). Based on the atomic descriptors (Quantitative Neighborhood of Atoms (QNA) and Multilevel Neighborhoods of Atoms (MNA)) and molecular (topological length, topological volume and lipophilicity) descriptors, we have developed 9 statistically significant QSAR consensus models that demonstrate high accuracy in predicting the lgk7 values for the compounds of training sets and appropriately predict lgk7 for the test samples. Moderate predictive power of these models is demonstrated using metrics of two categories: (1) based on the determination coefficients R2 (R2TSi, R20, Q2(F1), Q2(F2), RmTSi2¯) and based on the concordance correlation coefficient (CCC)); or (2) based on the prediction lgk7 errors (root mean square error (RMSEP), mean absolute error (MAE) and standard deviation (S.D.)) The RBF-SCR method has been used for selecting the descriptors. Our theoretical prognosis of the lgk7 for 8-PPDA, a known antioxidant, based on the consensus models well agrees with the experimental value measure in the present work. Thus, the algorithms for calculating the descriptors implemented in the GUSAR 2013 program allow simulating kinetic parameters of the reactions underling the liquid-phase oxidation of hydrocarbons.

Validation of Existing Arabic Language Reading Knowledge Instrument (SPSAMBA): Exploratory Factor Analysis (EFA)

This study aimed to review the Existing Arabic Language Reading Knowledge Instrument (SPSAMBA). A total of 150 trainee teachers in the field of Islamic Education and Arabic at the Institute of Teacher Education (IPG) were involved as respondents in this pilot study. Data analysis was descriptive using Alpha Cronbach reliability and factor exploration analysis (EFA) using SPSS software version 25. The results of the analysis found that the value of Alpha Cronbach obtained between 0.945-0.949 and the overall index value is 0.949. Results from the EFA showed five existing knowledge factors with Eigenvalues ​​each exceeding 1.0. The existing knowledge construct had a KMO Kaiser-Meyer-Olkin Measure of Sampling Adequacy value of 0.858> 0.5. It proved that the items were sufficient for inter-correlation and Bartlett’s Test of Sphericity (BToS) test was significant (Chi-Square 2157.699, p <0.05), the anti-image value (Measure of Sampling Adequacy - MSA) for item correlation exceeded 0.5 with all items accepted and the total variance value explained by the five factors was 61.97 per cent. The overall findings recorded that the items for the existing knowledge instruments could measure and answer the objectives of the study.

Children's Perceived Value: Conceptualization, Scale Development, and Validation

© 2020 New York University Perceived value among children is an important concept in consumer decisions, yet surprisingly no research has operationalized value for this consumer group. To address this omission, and following the guidelines of DeVellis (2016), this investigation reports the findings of a seven-stage process to develop a valid and reliable instrument for measuring perceived value among children aged 8–14 years. Value for children is conceptualized as a multidimensional construct capturing perceptions of what is received and what is given up, which differs from adult measures in terms of its composition and complexity. A 24-item scale is developed that shows internal consistency, reliability, construct validity, and nomological validity. We also demonstrate the validity of the new scale beyond an existing adult perceived value measure. Directions for future research and managerial implications of the new scale for studying children's consumer behavior are discussed.

Children's Perceived Value: Conceptualization, Scale Development, and Validation

© 2020 New York University Perceived value among children is an important concept in consumer decisions, yet surprisingly no research has operationalized value for this consumer group. To address this omission, and following the guidelines of DeVellis (2016), this investigation reports the findings of a seven-stage process to develop a valid and reliable instrument for measuring perceived value among children aged 8–14 years. Value for children is conceptualized as a multidimensional construct capturing perceptions of what is received and what is given up, which differs from adult measures in terms of its composition and complexity. A 24-item scale is developed that shows internal consistency, reliability, construct validity, and nomological validity. We also demonstrate the validity of the new scale beyond an existing adult perceived value measure. Directions for future research and managerial implications of the new scale for studying children's consumer behavior are discussed.

Bias factor, maximum bias and the E-value: insight and extended applications

Background Unmeasured confounding can bias the relationship between exposure and outcome. Sensitivity analyses generate bias-adjusted measures but these are not much used; this may change with the availability of the E-value (for evidence for causality in observational studies), appealing for its ease of calculation. However, as currently proposed, the E-value has some practical limitations that may reduce its use. Methods We first provide some insight into the relationship between two established measures for unmeasured confounding: ‘the bias factor’ and the maximum value this bias factor can take (‘the B bias’). These measures are the statistical foundation for the E-value. We use them to develop new E-value formulas for situations when it is not currently applicable such as e.g. when, not unusually, a negative relation between unmeasured confounder and outcome and a positive one with exposure are postulated. We also provide E-values on the odds ratio scale because, currently, even when using the odds ratio as the study measure in the calculation of E-value, the result is to be interpreted as a relative risk, which is somewhat inconvenient. Results The additional formulas for the E-value measure make it applicable in all possible scenarios defined by the combined directions between unmeasured confounder and both the exposure and outcome. In addition, E-value measures can now be interpreted as odds ratios if the observed results are reported on the same scale. Conclusions The E-value is part of newer sensitivity analyses methods for unmeasured confounding. We provide insight into its structure, underscoring its advantages and limitations, and expand its applications.

VALIDATION OF MATHEMATICS TEACHING PRACTICE INSTRUMENTS AMONG SECONDARY SCHOOL MATHEMATICS TEACHERS: EXPLORATORY FACTOR ANALYSIS (EFA)

This study aims to review the instruments of mathematics teaching practice among secondary school mathematics teachers. A total of 100 mathematics teachers were involved as respondents in this study. The data were analyzed descriptively by access to Alpha Cronbach's reliability and EFA analysis using SPSS software. The results of the analysis show that the Alpha Cronbach value is 0.934 which is more than 0.60. Results from the exploration factor analysis show four factors with Eigenvalues greater than 1.0. The KMO value (Kaiser-Meyer-Olkin) 0.867 > 0.6 indicates the items in the variable of attitude towards math are sufficient for inter-correlation. While the Bartlett Test was significant (Chi-Square 1521.621, p <0.05), an anti-image value (Measure of Sampling Adequacy, MSA) for items correlation exceeded 0.6. However, there are three items that need to be removed because the values obtained are less than 0.60, which were the items G11, G14, and G18. The value of the total variance explained by these three factors was 62.76 percent. Therefore, the overall findings indicate that the items for mathematics teaching practice instruments can measure and answer the study objectives.

VALIDATION MEASUREMENT, FACTOR ANALYSIS AND RELIABILITY OF TEACHER PERCEIVED USEFULNESS INSTRUMENTS ON SMARTPHONE USE AMONG SECONDARY SCHOOL TECHNOLOGY DESIGN TEACHERS

This study aims to review the instruments of perceived usefulness (PU) among secondary school technology design (RBT) teachers utilizing the use of smartphones in teaching and facilitation (PdPc). A total of 125 RBTs teachers were involved as respondents in this study. The data were analyzed descriptively by access to Alpha Cronbach's reliability and EFA analysis using SPSS software. The results of the analysis show that the Alpha Cronbach value was 0.782 for perceived usefulness, which was greater than 0.60. Results from the EFA show perceived usefulness with Eigenvalues above 1.0. Perceived usefulness construct with a KMO value (Kaiser-Meyer-Olkin) 0734 > 0.5 showed that the items were adequate for inter-correlation and that Bartlett's test was significant (Chi-Square 441.43, p <0.05), anti-image value (Measure of Sampling Adequacy - MSA) for a correlation of more than 0.5 items with four items D7, D8, D9, D10 and D11 to be excluded because the value obtained is less than 0.50 and the total variance value explained is 63.54 percent. The overall findings indicate that items for perceived usefulness can measure and answer the objectives of the study.