Search results for "Regression analysis"
showing 10 items of 807 documents
Integrated emitter local loss prediction using artificial neural networks.
2010
This paper describes an application of artificial neural networks (ANNs) to the prediction of local losses from integrated emitters. First, the optimum input-output combination was determined. Then, the mapping capability of ANNs and regression models was compared. Afterwards, a five-input ANN model, which considers pipe and emitter internal diameter, emitter length, emitter spacing, and pipe discharge, was used to develop a local losses predicting tool which was obtained from different training strategies while taking into account a completely independent test set. Finally, a performance index was evaluated for the test emitter models studied. Emitter data with low reliability were removed…
Assessing the efficiency of wastewater treatment plants: A double-bootstrap approach
2017
Abstract Benchmarking the performance of wastewater treatment plants (WWTPs) is essential for promoting their long-term sustainability. Recent research has applied data envelopment analysis (DEA) models to evaluate the efficiency of WWTPs providing a synthetic index of their performance. However, the traditional DEA is a deterministic method; therefore, regression analysis cannot be used to explore the external factors influencing efficiency scores. To overcome this limitation, in this study, a double bootstrap DEA model was used for the first time to compute the efficiency scores for a sample of WWTPs. The confidence intervals for efficiency scores were estimated for each facility. Results…
Board of director attributes: effects on financial performance in SMEs
2021
This paper analyses the relationship between board of director (BoD) attributes and financial performance in small and medium-sized enterprises (SMEs). Although SMEs are the backbone of world economies, most studies on this relationship focused on large companies and did not consider many typical or recommended processes and activities carried out by SME BoDs. We monitored a set of variables related to BoD attributes such as composition, characteristics, structure and processes for 184 Italian SMEs along with their financials over a 4-year period (2014–2017). We controlled for enterprise-specific characteristics such as annual sales growth, assets value, sales turnover, leverage, com pany s…
Young Innovative Companies and Access to Subsidies
2016
Young innovative companies (YICs) are becoming increasingly prominent in the debate on industrial policy because of their role as drivers of industry and the economy. The aim of this research was to determine which variables associated with the entrepreneur and the creation of YICs enable access to public entrepreneurship policies. This analysis compared Mas-Tur and Simon-Moya’s (2015) results (obtained using regression analysis) with results yielded by Qualitative Comparative Analysis (QCA). Using the QCA methodology, we identified causal configurations that lead companies to receive subsidies, or conversely, that lead companies not to receive subsidies. We thus observed differences in fin…
Enhanced extraction of astragalosides from Radix Astragali by negative pressure cavitation-accelerated enzyme pretreatment.
2010
The optimal conditions for extraction of astragalosides III and IV (AGs III and IV) in Radix Astragali by negative pressure cavitation-accelerated enzyme pretreatment were studied on the basis of a Box-Behnken design and response surface methodology. Experimental results showed that negative pressure, amount of enzyme and incubation temperature were the main factors governing the enzyme pretreatment of Radix Astragali. The optimum parameters were obtained as follows: negative pressure -0.08 Mpa, amount of enzyme 1.48% (w/w of materials) and incubation temperature 45 degrees C. Under the optimal conditions, the maximal extraction yields of AGs III and IV were 0.103 and 0.325 mg/g, which were…
Dietary acrylamide and physical performance tests: A cross-sectional analysis
2021
Background Dietary acrylamide is found in certain foods, such as deep frying, baking and roasting, and is associated with higher inflammatory and oxidative stress parameters. The association between dietary acrylamide and physical performance has not yet been explored. The aim of the study was to investigate the relationship between dietary acrylamide intake and physical performance tests in a large cohort of North American individuals affected by knee osteoarthritis or at high risk for this condition. Methods Dietary acrylamide intake was obtained through a food frequency questionnaire and reported in quartiles and as an increase in deciles. Physical performance was explored using the 20-…
Estimation of National Colorectal-Cancer Incidence Using Claims Databases
2012
Background.The aim of the study was to assess the accuracy of the colorectal-cancer incidence estimated from administrative data.Methods.We selected potential incident colorectal-cancer cases in 2004-2005 French administrative data, using two alternative algorithms. The first was based only on diagnostic and procedure codes, whereas the second considered the past history of the patient. Results of both methods were assessed against two corresponding local cancer registries, acting as “gold standards.” We then constructed a multivariable regression model to estimate the corrected total number of incident colorectal-cancer cases from the whole national administrative database.Results.The firs…
Impact of Transport Costs on International Trade: The Case of Spanish Ceramic Exports
2003
This paper aims to investigate the determinants of maritime and overland transport costs and the role they play in deterring trade across countries. We estimate a transport cost function using data on maritime and overland transport of the ceramic sector (tiles) obtained from interviews held with Spanish logistics operators. We also study the relationship between transport costs and trade and estimate an import demand model for ceramic products. Additionally, we present a discussion on the sensitivity of trade flows and transportation costs to the existence of back-hauling, special conditions for transport and number of reloads.1 The study of modal transport (overland versus maritime) and i…
Development Of An Econometric Model Case Study: Romanian Classification System
2015
Abstract The purpose of the paper is to illustrate an econometric model used to predict the lean meat content in pig carcasses, based on the muscle thickness and back fat thickness measured by the means of an optical probe (OptiGrade PRO).The analysis goes through all steps involved in the development of the model: statement of theory, specification of the mathematical model, sampling and collection of data, estimation of the parameters of the chosen econometric model, tests of the hypothesis derived from the model and prediction equations. The data have been in a controlled experiment conducted by the Romanian Carcass Classification Commission in 2007. The purpose of the experiment was to …
Estrategias para la elaboración de modelos estadísticos de regresión
2011
Multivariable regression models are widely used in health science research, mainly for two purposes: prediction and effect estimation. Various strategies have been recommended when building a regression model: a) use the right statistical method that matches the structure of the data; b) ensure an appropriate sample size by limiting the number of variables according to the number of events; c) prevent or correct for model overfitting; d) be aware of the problems associated with automatic variable selection procedures (such as stepwise), and e) always assess the performance of the final model in regard to calibration and discrimination measures. If resources allow, validate the prediction mo…