Search results for "regression"
showing 10 items of 2619 documents
Multivariate quality control studies applied to Ca(II) and Mg(II) determination by a portable method
1998
Made available in DSpace on 2022-04-28T19:53:14Z (GMT). No. of bitstreams: 0 Previous issue date: 1998-01-01 A portable or field test method for simultaneous spectrophotometric determination of calcium and magnesium in water using multivariate partial least squares (PLS) calibration methods is proposed. The method is based on the reaction between the analytes and methylthymol blue at pH 11. The spectral information was used as the X-block and the Ca(II) and Mg(II) concentrations obtained by a reference technique (ICP-AES) were used as the Y-block. Two series of analyses were performed, with a month's difference between them. The first series was used as the calibration set and the second on…
Calibration transfer in chemiluminescence analysis
2001
Abstract Direct standardization (DS) and piecewise direct standardization (PDS) methods are applied to multivariate standardization of chemiluminescence signals using PLS model as the calibration model. The linear concentration interval of the chemiluminescence determination was determined. This interval was located using univariate robust calibration by least median of squares (LMS) method. The linear calibration model was corroborated by conventional least-squares method. The standardization subset and window size were optimized by means of the prediction residual error sum of squares. Several instrumental sources of variability have been studied: the detection cell, instrument, batch ver…
Fetal growth and childhood acute lymphoblastic leukemia: Findings from the childhood leukemia international consortium
2013
Positive associations have been reported between measures of accelerated fetal growth and risk of childhood acute lymphoblastic leukemia (ALL). We investigated this association by pooling individual-level data from 12 case-control studies participating in the Childhood Leukemia International Consortium. Two measures of fetal growth – weight-for-gestational-age and proportion of optimal birth weight (POBW) – were analysed. Study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression, and combined in fixed effects meta-analyses. Pooled analyses of all data were also undertaken using multivariable logistic regression. Subgroup analy…
Impact of socio-economic position on cancer stage at presentation: Findings from a large hospital-based study in Germany
2016
We explored the relationship between socio-economic characteristics and cancer stage at presentation. Patients admitted to a university hospital for diagnosis and treatment of cancer provided data on their education, vocational training, income, employment, job, health insurance and postcode. Tumor stage was classified according to the Union International Contre le Cancer (UICC). To analyze disparities in the likelihood of late-stage (UICC III/IV vs. I/II) diagnoses, logistic regression models adjusting for age and gender were used. Out of 1,012 patients, 572 (59%) had late-stage cancer. Separately tested, increased odds of advanced disease were associated with post-compulsory education com…
Factors Associated with Prolonged Patient-Attributable Delay in the Diagnosis of Colorectal Cancer
2018
Purpose The delayed diagnosis of colorectal cancer (CRC) may be attributable to sociodemographic characteristics, to aspects of tumour histopathology or to the functioning of the health system. We seek to determine which of these factors most influences prolonged patient-attributable delay (PPAD) in the diagnosis and treatment of CRC. Materials and methods A prospective, multicentre observational study was conducted in 22 Spanish hospitals. In total, 1,785 patients were recruited to the study between 2010 and 2012 and underwent elective or urgent surgery. PPAD is considered to occur when the time elapsed between a patient presenting the symptom and him/her seeking attention from the primary…
Surveillance as determinant of long-term survival in non-transplanted hepatocellular carcinoma patients
2021
Purpose: We aimed at assessing the impact of surveillance on long-term survival in HCC patients. Methods: From the ITA.LI.CA database, we selected 1028 cases with long (≥5 years, LS group) and 2721 controls with short-term survival (<
Sun exposure and malignant lymphoma: A population-based case–control study in Germany
2007
Although some causes for malignant lymphoma are known their etiology is not well understood so far. We analyze the relationship between sun exposure and malignant lymphoma in a multicenter, population-based case-control study. Patients with malignant lymphoma (n = 710, 18-80 years) were prospectively recruited in 6 study regions in Germany. For each case, a gender, region and age-matched control was drawn from population-registers. In personal interviews, lifetime holidays spent in sunny climate, outdoor leisure activities and sunbed or sunlamp use were recorded. On basis of job task-specific supplementary questionnaires, an occupational physician assessed the cumulative working time outsid…
Fasting and weight-loss restrictive diet practices among 2,700 cancer survivors: results from the NutriNet-Santé cohort
2018
Nutrition is often used by cancer survivors as a lever to take charge of their own health. However, some dietary behaviors are not currently recommended for patients without medical supervision. Our study aimed at evaluating weight-loss restrictive diets and fasting practices among cancer survivors of the NutriNet-Sante cohort, as well as related socio-demographic and lifestyle factors. In October 2016, 2,741 cancer survivors had completed a specific questionnaire about their practices. Fasting and non-fasting patients (respectively dieting and non-dieting) were compared using logistic regression models. Analyses were weighted according to the age, gender, and cancer location distribution o…
Invitation to cervical cancer screening does increase participation in Germany: Results from the MARZY study
2016
The effect of different invitation models on participation in cervical cancer screening (CCS) was investigated in a randomized population-based cohort study in Germany. Participants were randomly selected via population registries and randomized into intervention Arm A (invitation letter) and Arm B (invitation letter and information brochure) or control Arm C (no invitation). The intervention and control arms were compared with regard to 3-year participation and the two invitation models were compared between intervention arms. Of the 7,758 eligible women aged 30-65 years, living in the city of Mainz and in the rural region of Mainz-Bingen, 5,265 were included in the analysis. Differences i…
Quantification of exposure to dioxins and furans in a cohort of workers of a herbicide producing plant in hamburg, FRG
1992
Abstract To assess the exposure to PCDD/Fs of a cohort of 1583 workers of a herbicide producing plant in Hamburg, FRG, investigated for cancer mortality, measurements of PCDD/Fs in fat tissue (n=48) or blood (n=64) were analyzed according to work histories in a subgroup of n=112 male workers. In a multiple regression analysis the time of work in the production of 2,4,5-T and 2,4,5-TCP, for the latter especially before 1957, correlated well with the levels of 2378-tetrachlorodibenzo-p-dioxin (TCDD). For most of the higher chlorinated isomers time of work in the thermic decomposition showed the strongest effect. The results confirm that the developed indicators are good proxis for exposure to…