SEARCH · PubMed Health

Results for “Regression Analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources

PubMed1982

Social experiences in childhood and adult psychiatric morbidity: a multiple regression analysis.

The effect of childhood experiences on adult psychiatric morbidity was examined in a community psychiatric survey. The Present State Examination was used to assess psychiatric morbidity. Childhood experiences assessed included childhood demographic factors and 'loss and deprivation' variables. The latter group comprised maternal and paternal deaths and separations and other disruptions in parental care 'Loss and deprivation' in combination accounted for between 4.5 and 5.5% of the variance in adult psychiatric morbidity.

Adolescent↗

PubMed1997

Semiparametric regression analysis for recurrent event interval counts.

This paper deals with analysis of data from longitudinal studies where the rate of a recurrent event characterizing morbidity is the primary criterion for treatment evaluation. We consider clinical trials which require patients to visit their clinical center at successive scheduled times as part of follow-up. At each visit, the patient reports the number of events that occurred since the previous visit, or an examination reveals the number of accumulated events, such as skin cancers. The exact occurrence times of the events are unavailable and the actual patient visit times typically vary randomly about the scheduled follow-up times. Each patient's record thus consists of a sequence of clinic visit dates, event counts corresponding to the successive time intervals between clinic visits, and baseline covariates. We propose a semiparametric regression model, extending the fully parametric model of Thall (1988, Biometrics 44, 197-209), to estimate and test for covariate effects on the rate of events over time while also accounting for the possibly time-varying nature of the underlying event rate. Covariate effects enter the model parametrically, while the underlying time-varying event rate is modelled nonparametrically. The method of Severini and Wong (1992, Annals of Statistics 20, 1768-1802) is used to construct asymptotically efficient estimators of the parametric component and to specify their asymptotic distribution. A simulation study and application to a data set are provided.

Biometry↗

PubMed1995

A single-center multiple regression analysis of covariates associated with long-term cadaveric renal allograft survival: further improvement of long-term results with CsA.

This single center analysis shows further improvement in the already excellent long-term, cadaveric renal allograft survival with Aza since the introduction of CsA. In contrast to the findings from the UCLA/UNOS multicenter registries, these results support other observations that the type of maintenance immunosuppression does indeed influence the long-term attrition rate of cadaveric, renal allografts.

Adult↗

PubMed2003

[The regression analysis of the in hospital medical staffs infection rate and the application of the isolation measures including the emergency-isolation radiology information system].

OBJECTIVE: To analyze the relationship between the rate of the in-hospital medical staff SARS infection and the measure of isolation which including the application of the emergency-isolation radiology information system (EIRIS) in polyclinic. METHODS: The groups were classified according to the application of the prevention and protection measure. Group A referred to the stage before the declaration of infectious area was made. Group B was defined as the stage in which the application of common measures of the prevention and protection were made, but the isolation measure was not taken (the suspected or diagnosed cases had the chest X ray film examination in the department of radiology). Group C was the stage after the startup of the isolation measure including the application of EIRIS. the number of the diagnosed cases, the medical staffs exposed, and the diagnosed cases of medical staffs were recorded. RESULTS: In group A, the infectious rate of in-hospital medical staffs showed a marked ascending trend with the regression coefficient of 0.000545, P = 0.04. The rate showed a little descending trend in Group B compared with that in Group A with the regression coefficient of 0.000164, P = 0.140. While marked descending trend compared with group A was demonstrated in group C with the regression coefficient of 0.000037, P = 0.02. CONCLUSION: The trend of the in-hospital medical staffs infection rate changed with different style of prevention and protection measures. With the application of the common measure of the prevention and protection, the rate was significantly lower than that in group A. After the application of the isolation measures including EIRIS, the rate showed the descending trend much further.

Emergencies↗

PubMed1989

Predicting contraceptive use in Bangladesh: a logistic regression analysis.

Family planning knowledge, attitude and practice surveys typically assess respondents' reproductive attitudes and intentions to use contraception. Longitudinal observation of individual respondents nevertheless shows that such questions are not strongly predictive of subsequent behaviour. This study examines 3 years' data which show that a set of such responses to questions are nevertheless substantially superior in predicting behaviour than any single indicator. Thus statistical techniques which bring into account the apparent multidimensionality of contraceptive motivation can greatly improve upon the estimation of future practice of family planning in a population.

Adult↗

PubMed1995

Quantification of pneumothorax size on chest radiographs using interpleural distances: regression analysis based on volume measurements from helical CT.

OBJECTIVE: The aim of this study was to define the relationship between interpleural distance measurements on an erect posteroanterior chest radiograph and pneumothorax size as measured by helical CT in a series of patients. SUBJECTS AND METHODS: Twenty pneumothoraces from 19 patients (10 males, nine females) were analyzed. Most pneumothoraces were on the right side (n = 16). The etiology was spontaneous in seven patients and iatrogenic in thirteen. All patients underwent an erect inspiratory posteroanterior radiograph and a helical CT scan of the thorax on the same visit to the radiology department. The interpleural distance was measured at three locations and the figures added together. Following helical CT of the thorax, the percentage pneumothorax size was calculated by drawing regions of interest around the relevant hemithorax and lung on 10-mm reconstructed slices. A scattergram of the sum of interpleural distances in centimeters versus percentage pneumothorax size was plotted. RESULTS: Analysis of results showed that percentage pneumothorax size could be calculated by the formula Y = 4.2 + [4.7 x (A + B + C)], r = .98, p < .0001. CONCLUSION: This study identified a formula for accurately calculating percentage pneumothorax size as determined by helical CT from an erect posteroanterior radiograph. Using this formula with the clinical status of the patient should more easily identify patients requiring active intervention.

Adolescent↗

PubMed1986

Microcomputer-based nonlinear regression analysis of ligand-binding data: application of Akaike's information criterion.

Akaike's information criterion (AIC) (Akaike, H., IEEE Trans. Automat. Contr. AC-19, 716-723 (1974)) was applied to estimate statistically the number of classes of binding sites from ligand-binding data. Several sets of data were analyzed by both the AIC method and the F-test method. Good agreement was obtained between results from both methods. The present results suggest that the AIC method can be a good alternative to the F-test to estimate the number of classes of sites.

Animals↗

PubMed2005

Decolourization of aqueous dye solutions by a novel adsorbent: application of statistical designs and surface plots for the optimization and regression analysis.

Adsorption of Neolan Blue 2G (Acid Blue 158) and Basic Methylene Blue (Basic Blue 9) was investigated using a hybrid adsorbent that was prepared by pyrolysing a mixture of carbon and flyash at 1:1 ratio. A 2(4) full factorial central composite design with nine replicates at the center point and thus a total of 31 experiments were successfully employed for batch experimental design and analysis of the results. The combined effect of pH, temperature, particle size and time on the dye adsorption was studied. An empirical model was developed and validated applying ANOVA analysis incorporating interaction effects of all parameters and optimized using response surface methodology. The optimum pH, temperature, particle size and time were found to be 2.20, 27.85 degrees C, 0.0565 mm, 245 min, respectively, for Acid Blue 158 and those for Basic Blue 9 were 13.40, 28.45 degrees C, 0.0555 mm and 230 min, respectively. Complete removal (100%) was observed for both the dyes using the hybrid adsorbent.

Adsorption↗

PubMed2004

Prognostic factors for early gastric cancer in France: Cox regression analysis of 332 cases.

Early gastric cancer (EGC) is defined as a lesion in which the depth of invasion is limited to the mucosa, submucosa, or both regardless of lymph node status; moreover, it has an excellent prognosis, with a 5-year survival rate of more than 90%. We aimed to determine the prognostic factors for EGC in a large Western series. Over a 10-year period from January 1979 to December 1988 a series of 332 patients (mean age 64 years) with EGC were operated on in 23 centers (two French Associations for Surgical Research). The clinicopathologic data retrospectively and screened it for prognostic effect. The mean follow-up for the 332 EGC patients was 80 months. Postoperative mortality was 4% among 243 partial and 89 total gastric resections. The overall 5- and 7-year survival rates were 82% and 72%, respectively. The cumulative 5- and 7-year survival rates (mean follow-up 80 months) were 92.0% and 87.5%, respectively, excluding both operative and unrelated mortality. There was no significant difference in survival between partial and total gastric resection for lesions located in the lower third of the stomach ( p > 0.6). When survival data (excluding postoperative deaths) were analyzed using univariate analysis and Cox's proportional hazards model, lymphatic involvement ( p = 0.01), the site of the tumor in the upper two-thirds of the stomach ( p = 0.02), and submucosal lesions ( p = 0.049) showed a significant effect on predicting a poor prognosis. These results suggest that because of its prognostic value lymphadenectomy should be performed in addition to gastric resection for adequate classification of EGCs. Follow-up might be required only for patients with at least one poor prognostic factor.

Adenocarcinoma↗

PubMed1986

A multiple regression analysis of variables influencing birthweight.

Birthweights recorded in a rural maternity centre (1979-1981) in Tanzania are related to parity, gestational age, maternal weight, sex of the child, maternal weight gain in pregnancy, intensity of antenatal care, and systolic blood pressure. The interrelations between these variables were analysed so as to discover their relative importance as determinants of birthweight variations. Only lengths of gestation, parity, sex, and maternal weight were retained in a general model explaining 29 percent of the total variance of birthweight. Short gestation accounted for 70 percent of all cases with low birthweight. For intervention purposes the further study of the causes of short gestation is therefore recommended.

Birth Weight↗

PubMed2005

Using return on equity and total profit margin to evaluate hospital performance in the U.S.: a piecewise regression analysis.

We investigated hospital profitability by comparing Total Profit Margin (TPM) and Return on Equity (ROE) as measures of profitability, while controlling for inflation and other salient factors. We controlled for variables such as, Disproportionate Share Hospital status, location, type of ownership control, teaching status, conversion to or from nonprofit status, Critical Access Hospital status, sole Medicare provider status, case mix adjusted patient length of stay, bed size, number of employees, and occupancy rate. We allowed for nonlinearities in our model, and used 1996 and 1998 data in our analysis to bridge potential effects of the Balanced Budget Act of 1997. Most of the hospitals we examined were nonprofit organizations that did not convert their type of ownership control. As a consequence, we found TPM to be a better measure of profitability than ROE, and profitability was mainly influenced by location, size, occupancy rate, volume of Medicare and Medicaid patients, and teaching status. Our results clarify the primary factors associated with profitability for our sample hospitals, and will assist creditors, managers and regulators in their assessments of comparative hospital financial performance.

Data Collection↗

PubMed1991

Estimation of the absorbed dose in radiation-processed food--1. Test of the EPR response function by a linear regression analysis.

Free radicals produced in chicken bone tissue by 137Cs gamma-rays were measured using electron paramagnetic resonance spectroscopy. The yield of radicals was found to be proportional to the absorbed dose. Additive re-irradiation of previously irradiated bones is the basis of a method to estimate the absorbed dose in radiation-processed foods. The ability of the method to provide accurate dose assessments for a range of doses (0.5-7.4 kGy) is tested here. A linear fit to the data yields reasonable dose estimates for bone irradiated less than 2 kGy, but fails at the higher doses using a linear approximation to the dose response. These data and their implications are discussed.

Animals↗

PubMedDate not supplied

Nonlinear least-squares regression analysis by a simplex method using differential equations containing Michaelis-Menten type rate constants.

Computer curve fittings were carried out to observed data as well as theoretically generated plasma concentrations of several drugs, using differential equations which contained nonlinear Michaelis-Menten type rate constants to discuss problems of initial parameter estimation in pharmacokinetic analysis. Calculation based on two different algorithms, each carried out by using SIMP (simplex method) and NONLIN (modified Gauss-Newton method) produced similar results. However, occasional divergence or unreasonable solutions occurred in a later case, when assumed values of Km and Vmax were used as initial parameters. A combined use of SIMP and NONLIN in which calculated values by SIMP were used as initial values for NONLIN, was shown to be effective to analyse plasma concentration data of indocyanine green bearing difficulty in estimating initial values. It is suggested that the successive method is useful for the curve fitting of plasma concentration with nonlinear pharmacokinetic rate processes.

Models, Statistical↗

PubMed1989

[Factors in long-term survival after total portal systemic shunting: a multiple regression analysis].

163 patients with portal hypertension underwent portal systemic shunting at PUMC hospital during the time of 1970's. There were 98 cases had central spleno-renal shunts. 38 had portacaval shunts and 27 had meso-caval shunts. The live function in this group are A-40%, B-55% and C-5%. The totaled operative mortality was 11.0%, and the totaled 5 years survival was 59.5%. The analysis reveals that: (1) The long-term survival and the patient's life quality were significant influenced by liver function and the type of shunting; (2) The mortality of emergency operation was significant higher than elective shunting surgery (30.0% vs 4.6%); (3) The cephalopathy and rebleeding rate were correlated with the type of shunting, liver function and the diameter of shunt; (4) The patient with A or B liver function could accept either elective or emergency operation, but emergency surgery should be carefully chosen for. The mortality was higher than 80% in emergency shunting for the patient with liver function C.

Adolescent↗

PubMed1992

Prediction of low birth weight outcome in Thailand: multiple regression analysis.

In the present study the risk approach using maternal risk factors for LBW newborns in Thailand is applied. The study may be considered as a managerial tool for developing local strategies and is particularly useful in maternal and child health care. The main objective is to develop a model to predict LBW outcome with an aim to screen those at risk at the level of health centres, district and provincial hospitals. Using MLR analysis, it is concluded that Model I and Model II (Table 3 and 4) can be used to predict which pregnant women are likely to deliver LBW newborns. The prediction can be made as early as the first trimester. If the prediction is shown to be accurate, the two models will be very helpful for use in Thai people. For general use, the investigators believe that Model I will be appropriate for application at the level of provincial and district hospitals, while Model II should be used at the health centre level peripheral to the health delivery system.

Case-Control Studies↗

PubMed1975

Unbalanced regression analysis with residuals having a covariance structure of intra-class form.

Let Yi be an ni X 1 vector of observations, Xi an ni X p matrix of known values, and beta an unknown p X 1 with the structure Yi = Xi beta + epsilon i, where the covariance matrix of epsilon i is of intra-class form, that is Cov (epsilon i) = sigma2[(1 - rho) Ii + rho e i e i'] where Ii is the ni X ni identity matrix and e i is the ni X 1 vector each element of which is unity. This article develops the maximum likelihood estimators of beta, sigma2, and rho when one observes N pairs (Xi, Yi). This situation arises typically in biological problems where one samples clusters of related organisms. The estimation procedure is illustrated in a commonly occurring genetics situation.

Adenosine Triphosphate↗

PubMed2004

Semiparametric regression analysis on longitudinal pattern of recurrent gap times.

In longitudinal studies, individual subject may experience recurrent events of the same type over a relatively long period of time. The longitudinal pattern of gaps between successive recurrent events is often of great research interest. In this article, the probability structure of the recurrent gap times is first explored in the presence of censoring. According to the discovered structure, we introduce the stratified proportional reverse-time hazards models with unspecified baseline functions to accommodate individual heterogeneity, when the longitudinal pattern parameter is of main interest. Inference procedures are proposed and studied by way of proper riskset construction. The proposed methodology is demonstrated by the Monte Carlo simulations and an application to a well-known Denmark schizophrenia cohort study data set.

Age of Onset↗

PubMed1997

Technical note: regression analysis in adult age estimation.

Accurate estimation of human adult age has always been a problem for anthropologists, archaeologists and forensic scientists. The main factor contributing to the difficulties is the high variability of physiological age indicators. However, confounding this variability in many age estimation applications is a systematic tendency for age estimates, regardless of physiological indicator employed, to assign ages which are too high for young individuals, and too low for older individuals. This paper shows that at least part of this error is the inevitable consequence of the statistical procedures used to extract an estimate of age from age indicators, and that the magnitude of the error is inversely related to how well an age indicator is correlated with age. The use of classical calibration over inverse calibration is recommended for age estimation.

Adolescent↗