CONTEXT Levels of modern contraceptive knowledge and use among people living in rural areas of Guatemala differ substantially from those of people living in urban areas. Understanding the pace and extent of rural-to-urban migrants' adoption of urban contraceptive practices is important in determining if there is a strong need for migrant-focused reproductive health programs. METHODS Bivariate...

Multivariate calibration methods (partial least squares calibration, back propagation multilayer perceptrons networks, radial basis functions and generalized regression neural networks) were applied to the simultaneous fluorometric quantification of levofloxacin, garenoxacin and grepafloxacin, without previous separation steps. A data matrix was obtained by registering the emission spectra of m...

a new fourier transform-infra red (ft-ir) spectrometric method was developed for assaying hydrochlorothiazide (hct) and enalapril maleate (enm) in binary solid pharmaceutical formulations. multivariate partial least squares (pls) method was used for calibration of derivative spectral data. acetonitrile was used as solvent due to its spectral transparency and adequate solubility of analytes in i...

Simultaneous spectrophotometric determination of salicylamide and paracetamol by H-point standard addition method (HPSAM) and partial least squares (PLS) calibration is described. The results showed that simultaneous determinations could be performed with the ratio 0.2:5–20:1 for salicylamide – paracetamol. A partial least – squares multivariate calibration method for the analysis of binary mix...

The objective of this paper is to present a review of different calibration and classification methods for functional data in the context of chemometric applications. In chemometric, it is usual to measure certain parameters in terms of a set of spectrometric curves that are observed in a finite set of points (functional data). Although the predictor variable is clearly functional, this problem...

Multivariate calibration is an important tool for spectroscopic measurement of analyte concentrations. We present a detailed study of a hybrid multivariate calibration technique, constrained regularization (CR), and demonstrate its utility in noninvasive glucose sensing using Raman spectroscopy. Similar to partial least squares (PLS) and principal component regression (PCR), CR builds an implic...

Calibration estimation is a method of adjusting the original design weights to improve the survey estimates by using auxiliary information such as the known population total (or mean) of the auxiliary variables. A calibration estimator uses calibrated weights that are determined to minimize a given distance measure to the original design weights while satisfying a set of constraints related to ...