Search results for "Regression analysis"
showing 10 items of 807 documents
Analysis of the sensitivity to the systematic error in least-squares regression models
2004
An algorithm that calculates the sensitivity to the systematic error of the fitted parameters of a least-squares regression model, with respect to the known parameters, is developed. The algorithm can be applied to mechanistic and empirical models, obtained by linear and non-linear regression, including principal component and partial least-squares. It can be useful in identifying those parameters or calibration regions that can influence other parameters and the response mostly, and thus, whose accuracy should be particularly procured. Other applications are the weighing of experimental points and the comparison of different models and regression methods in terms of its ability of amplifyi…
Psychological intimate partner violence: the major predictor of posttraumatic stress disorder in abused women.
2004
Intimate partner violence (IPV) significantly impacts women mental and physical wellbeing and therefore represents a worldwide public health problem. A clear association between IPV and increased risk to develop posttraumatic stress disorder (PTSD) has been documented. However, few studies examined how different features of IPV (physical, psychological, sexual) interact with other traumatic stress experiences (physical, psychological and sexual childhood abuse and adulthood victimization by other/s than the partner) in determining PTSD. Women abused by the partner (n=75) were compared with non-abused control women (n=52). Information about sociodemographic profile and relevant personal char…
An Exploration of Organizational Assimilation Among State-Owned, Private-Owned, and Foreign-Invested Enterprises in China
2017
This study explores organizational assimilation in Chinese organizations. To reflect the Chinese context more accurately, the present study compared employees working in three different kinds of organizations: state-owned enterprises (SOEs), private-owned enterprises (POEs), and foreign-invested enterprises (FIEs). Data collected from 220 full-time employees were analyzed using multiple regression analysis. Regression analyses demonstrated that employees’ level of organizational assimilation was significantly influenced by organizational type: Employees in SOEs reported the highest level and employees in FIEs reported the lowest level of organizational assimilation. peerReviewed
Gaussian processes retrieval of leaf parameters from a multi-species reflectance, absorbance and fluorescence dataset.
2013
Abstract: Biochemical and structural leaf properties such as chlorophyll content (Chl), nitrogen content (N), leaf water content (LWC), and specific leaf area (SLA) have the benefit to be estimated through nondestructive spectral measurements. Current practices, however, mainly focus on a limited amount of wavelength bands while more information could be extracted from other wavelengths in the full range (400-2500 nm) spectrum. In this research, leaf characteristics were estimated from a field-based multi-species dataset, covering a wide range in leaf structures and Chl concentrations. The dataset contains leaves with extremely high Chl concentrations (>100 mu g cm(-2)), which are seldom es…
Gas chromatographic study of acetyl derivatives of chlorinated 4-hydroxybenzaldehydes
1982
The GC retention times of 4-hydroxybenzaldehyde and its chloro derivatives have been measured on three nonpolar capillary columns. Multiple linear regression analysis has been used to explain the mobility of chlorinated compounds relative to the reference compound 4-hydroxybenzaldehyde. The most important effects have shown to be due to the number of chlorine atoms and the substituents ortho to the formyl group. Other effects have also been observed but found to be unable to explain the GC data.
Calculation of chromatographic parameters by molecular topology: sulphamides
1994
This investigation was undertaken to test the ability of the molecular connectivity model to predict RF values in thin-layer chromatography (TLC) for a group of sulphamides using multi-variable regression equations with multiple correlation coefficients, standard error of estimate, F-Snedecor function values and Student's t-test as criteria of fit. Regression analyses showed that the molecular connectivity model predicts the values for this property in different silica gel stationary phases and different polar mobile phases. Corresponding stability and random studies were made on the selected prediction models which confirmed their goodness of fit. The results also demonstrated that differe…
Prediction of wheat dough W and P/L inflation test parameters by capillary zone electrophoresis of a protein extract followed by multivariate regress…
2004
A procedure for the evaluation of the wheat flour hardness, based on capillary electrophoresis of a protein extract in an isoelectric acidic buffer, was developed. The 13 flour samples were extracted twice, and two injections of each extract were made. Separations were performed in a background electrolyte (BGE) containing 40 mM aspartic acid, 6 M urea, and 0.5% hydroxyethylcellulose at 60 degrees C. Using the normalized and corrected areas of 79 peaks and peak groups, a partial least squares regression (PLS1) model was able to predict the flour strength or dough deformation work (W) and the dough tenacity/extensibility ratio (P/L) (Alveograph parameters) with an average relative standard d…
Adaptive trial design: a general methodology for censored time to event data.
2008
Adaptive designs allow a clinical trial design to be changed according to interim findings without inflating type I error. The Inverse Normal method can be considered as an adaptive generalization of classical group sequential designs. The use of the Inverse Normal method for censored survival data was demonstrated only for the logrank statistic. However, the logrank statistic is inefficient in the presence of nuisance covariates affecting survival. We demonstrate, how the Inverse Normal method can be applied to Cox regression analysis. The required independence between test statistics of the different stages of the trial can be obtained by two different approaches. One is using the indepen…
An Extension of the DgLARS Method to High-Dimensional Relative Risk Regression Models
2020
In recent years, clinical studies, where patients are routinely screened for many genomic features, are becoming more common. The general aim of such studies is to find genomic signatures useful for treatment decisions and the development of new treatments. However, genomic data are typically noisy and high dimensional, not rarely outstripping the number of patients included in the study. For this reason, sparse estimators are usually used in the study of high-dimensional survival data. In this paper, we propose an extension of the differential geometric least angle regression method to high-dimensional relative risk regression models.
Estimation of confidence limits for descriptive indexes derived from autoregressive analysis of time series: Methods and application to heart rate va…
2017
The growing interest in personalized medicine requires making inferences from descriptive indexes estimated from individual recordings of physiological signals, with statistical analyses focused on individual differences between/within subjects, rather than comparing supposedly homogeneous cohorts. To this end, methods to compute confidence limits of individual estimates of descriptive indexes are needed. This study introduces numerical methods to compute such confidence limits and perform statistical comparisons between indexes derived from autoregressive (AR) modeling of individual time series. Analytical approaches are generally not viable, because the indexes are usually nonlinear funct…