scholarly journals A Review on Variable Selection in Regression Analysis

Econometrics ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 45 ◽  
Author(s):  
Loann Desboulets
Keyword(s):  
Variable Selection ◽  
Stepwise Regression ◽  
Empirical Work ◽  
Selection Procedures ◽  
Partially Linear ◽  
Automatic Model Selection ◽  
Wide Range ◽  
Long Time ◽  
Model Structures ◽  
Theoretical Side

In this paper, we investigate several variable selection procedures to give an overview of the existing literature for practitioners. “Let the data speak for themselves” has become the motto of many applied researchers since the number of data has significantly grown. Automatic model selection has been promoted to search for data-driven theories for quite a long time now. However, while great extensions have been made on the theoretical side, basic procedures are still used in most empirical work, e.g., stepwise regression. Here, we provide a review of main methods and state-of-the art extensions as well as a topology of them over a wide range of model structures (linear, grouped, additive, partially linear and non-parametric) and available software resources for implemented methods so that practitioners can easily access them. We provide explanations for which methods to use for different model purposes and their key differences. We also review two methods for improving variable selection in the general sense.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

Comperehencive review of Tankana

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Dr. Jyotsna Sankpal ◽  
Dr. Jyotsna Takalikar
Keyword(s):  
Heart Disease ◽  
Medical Science ◽  
Menstrual Disorders ◽  
Therapeutic Applications ◽  
Indian Medical ◽  
Wide Range ◽  
Long Time

Rasa Shastra and Bhaishajya Kalpana is branch of the ancient Indian medical science based on herbs and herbo-mineral preparation. Tankana has been described under Uparasa Tankana, which is one among the Kshara Trayas has been used since very long time in Ayurveda. It has a wide range of therapeutic applications, including diseases like Varna (ulcers), Shvasa (asthma), Kasa (cough), Hrudya (beneficial to heart disease), Streepushpajanana (menstrual disorders) etc. It is used in the form of compound formulations like Parpati, Kupipakwa, Khalvee Rasayana, Churna, Vati, Lepa etc. In this paper Tankana Shodhana procedure, different synonyms, dose, Anupana, indications and different formulations containing Tankana Bhasma has been discussed.

scholarly journals TARGET MODAL SPLIT MODEL

Transport ◽  
2012 ◽  
Vol 26 (4) ◽  
pp. 418-424 ◽  
Author(s):  
Valentina Basarić ◽  
Jadranka Jović
Keyword(s):  
Public Transport ◽  
Stepwise Regression ◽  
Statistical Data ◽  
Transport Policy ◽  
Wide Range ◽  
Policy Measures ◽  
Novi Sad ◽  
The Relationship ◽  
The City ◽  
Statistical Results

The research presented in this paper is aimed at defining a model that enables the management of the relationship between private vehicles and public transport applying the available instruments of city transport policy such as parking policy and public transport policy measures. Statistical data used for modelling is sourced from the database in a wide range of EU cities. The target model was developed in the form of stepwise regression analysis. Very favourable statistical results were obtained, and the subsequent tests on the city of Novi Sad (250000 inhabitants) led to the conclusion that the obtained results were suitable for implementation in practice. The results of the implemented procedure are of great importance for the enhancement of the existing transport policies in cities, as they enable the development of strategies for finding combinations of instruments that would bring the transport system and urban environment into a desired-viable rather than consequential condition.

scholarly journals Physical Properties of Thermoplastic Starch Derived from Natural Resources and Its Blends: A Review

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1396
Author(s):  
Z. N. Diyana ◽  
R. Jumaidin ◽  
Mohd Zulkefli Selamat ◽  
Ihwan Ghazali ◽  
Norliza Julmohammad ◽  
...  
Keyword(s):  
Thermoplastic Starch ◽  
Natural Fibre ◽  
Polymer Materials ◽  
Secondary Pollution ◽  
Wide Range ◽  
Potential Applications ◽  
Long Time ◽  
To Come ◽  
Main Component ◽  
Significant Attention

Thermoplastic starch composites have attracted significant attention due to the rise of environmental pollutions induced by the use of synthetic petroleum-based polymer materials. The degradation of traditional plastics requires an unusually long time, which may lead to high cost and secondary pollution. To solve these difficulties, more petroleum-based plastics should be substituted with sustainable bio-based plastics. Renewable and natural materials that are abundant in nature are potential candidates for a wide range of polymers, which can be used to replace their synthetic counterparts. This paper focuses on some aspects of biopolymers and their classes, providing a description of starch as a main component of biopolymers, composites, and potential applications of thermoplastics starch-based in packaging application. Currently, biopolymer composites blended with other components have exhibited several enhanced qualities. The same behavior is also observed when natural fibre is incorporated with biopolymers. However, it should be noted that the degree of compatibility between starch and other biopolymers extensively varies depending on the specific biopolymer. Although their efficacy is yet to reach the level of their fossil fuel counterparts, biopolymers have made a distinguishing mark, which will continue to inspire the creation of novel substances for many years to come.

Guiding Principals: Middle-Manager Coaching and Human-Capital Reform

2020 ◽  
Vol 122 (10) ◽  
pp. 1-50
Author(s):  
Susan Bush-Mecenas ◽  
Julie A. Marsh ◽  
Katharine O. Strunk
Keyword(s):  
Professional Development ◽  
Human Capital ◽  
Policy Implementation ◽  
Survey Data ◽  
Empirical Work ◽  
Think Aloud ◽  
High Quality ◽  
Wide Range ◽  
Role Of Principal

Background/Context School leaders are central to state and district human-capital reforms (HCRs), yet they are rarely equipped with the skills to implement new evaluation, professional development, and personnel data systems. Although districts increasingly offer principals coaching and training, there has been limited empirical work on how these supports influence principals’ HCR-related practices. Purpose Drawing on a two-year, mixed-methods study in the Los Angeles Unified School District (LAUSD), this article examines the role of principal supervisors in HCRs. We ask: What role did principal supervisors (Instructional Directors [IDs]) play in the implementation of human-capital reforms? What did high-quality coaching on the part of IDs look like in this context? Research Design Our two-part analysis draws upon survey and interview data. First, we conducted descriptive analyses and significance testing using principal and ID survey data to examine the correlations among principals’ ratings of ID coaching quality, ID coaching practices, and principals’ implementation of HCRs. Second, we conducted in-depth interviews, using a think-aloud protocol, with two sets of IDs—those consistently highly-rated and those with mixed ratings—who were identified using principals’ reports of coaching quality. Following interview coding, we created various case-ordered metamatrix displays to analyze our qualitative data in order to identify patterns in coaching strategy and approach across IDs, content, and contexts. Findings First, our survey data indicate that receiving high-quality coaching from IDs is correlated with stronger principal support for and implementation of HCRs. Our survey findings further illustrate that IDs support a wide range of principals’ HCR activities. Second, our think-aloud interviews with case IDs demonstrate that coaching strategy and approach vary between consistently highly-rated and mixed-rated coaches: Consistently highly-rated IDs emphasize the importance of engaging in, or defining HCR problems as, joint work alongside principals, while mixed-rated IDs often emphasize the use of tools to guide principal improvement. We find that, on the whole, the consistently highly-rated IDs in our sample employ a nondirective approach to coaching more often than mixed-rated coaches. Conclusions These findings contribute to a growing literature on the crucial role of principal supervisors as coaches to improve principals’ instructional leadership and policy implementation. While exploratory, this study offers the first steps toward building greater evidence of the connections between high-quality coaching and policy implementation, and it may have implications for the design and implementation of professional development for principal supervisors and the selection and placement of supervisors with principals.

scholarly journals ETHNOBOTANICAL, PHYTOCHEMICAL, AND PHARMACOLOGICAL PROPERTIES OF NEPENTHES SPECIES: A REVIEW

2017 ◽  
Vol 10 (11) ◽  
pp. 16 ◽  
Author(s):  
Shuaibu Babaji Sanusi ◽  
Mohd Fadzelly Abu Bakar ◽  
Maryati Mohamed ◽  
Siti Fatimah Sabran ◽  
Muhammad Murtala Mainasara
Keyword(s):  
Folk Medicine ◽  
Therapeutic Agents ◽  
Bioactive Components ◽  
Pharmacological Activities ◽  
Crude Extracts ◽  
Gastrointestinal Discomfort ◽  
Wide Range ◽  
Long Time ◽  
Phytochemical Compounds ◽  
Ethnobotanical Uses

The genus Nepenthes (Nepenthaceae) has been utilized in folk medicine for a long time in India and Southeast Asia countries. They are used in the treatment of leprosy, cholera, night blindness, gastrointestinal discomfort, dysentery, stomachache, and bed-wetting among others. This review highlights the ethnobotanical uses, phytochemicals, and pharmacological activities of both crude extracts and pure bioactive compounds of Nepenthes spp. The phytochemical compounds isolated from Nepenthes species include flavonoids, terpenoids, tannins, alkaloids, and steroids among other phytochemicals. A wide range of pharmacological activities was exhibited by the crude extracts and pure bioactive components such as antibacterial, antifungal, antimalarial antioxidant, antidiabetic, antiosteoporotic, anti-inflammatory, cytotoxicity, and hypolipidemic activities. This review revealed that many active compounds are present in Nepenthes spp. However, many pharmacological screenings such as anticancer, antiviral, wound healing, antihelminthic, antidiarrheal properties, among others have not been carried out yet. Therefore, more biological investigations and phytochemical screenings are required to fully explore the genus Nepenthes which may lead to development of new therapeutic agents.  

Comparison of Four Friction Models: Feature Prediction

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
Yun-Hsiang Sun ◽  
Tao Chen ◽  
Christine Qiong Wu ◽  
Cyrus Shafai
Keyword(s):  
Numerical Model ◽  
Viscous Friction ◽  
Friction Model ◽  
Dynamic Features ◽  
Numerical Predictions ◽  
Wide Range ◽  
Model Predictions ◽  
Friction Models ◽  
Parameter Identifications ◽  
Model Structures

In this paper, we provide not only key knowledge for friction model selection among candidate models but also experimental friction features compared with numerical predictions reproduced by the candidate models. A motor-driven one-dimensional sliding block has been designed and fabricated in our lab to carry out a wide range of control tasks for the friction feature demonstrations and the parameter identifications of the candidate models. Besides the well-known static features such as break-away force and viscous friction, our setup experimentally demonstrates subtle dynamic features that characterize the physical behavior. The candidate models coupled with correct parameters experimentally obtained from our setup are taken to simulate the features of interest. The first part of this work briefly introduces the candidate friction models, the friction features of interest, and our experimental approach. The second part of this work is dedicated to the comparisons between the experimental features and the numerical model predictions. The discrepancies between the experimental features and the numerical model predictions help researchers to judge the accuracy of the models. The relation between the candidate model structures and their numerical friction feature predictions is investigated and discussed. A table that summarizes how to select the most optimal friction model among a variety of engineering applications is presented at the end of this paper. Such comprehensive comparisons have not been reported in previous literature.

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