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At least 469 records · Page 26Linked to original sources
PubMed1988

Some statistical analysis issues at the World Fertility Survey.

"The World Fertility Survey carried out cross-sectional probability surveys of fertility in more than 40 developing countries between 1972 and 1984. Statistical issues in regression analysis of the data are reviewed, including treatment of interactions, the selection of regressor variables, and appropriate linear models for rate variables. Similar issues arise in many other applications of regression to observational data."

Birth Rate↗
PubMedDate not supplied

A powerful, yet easy to use, computerized analysis of competitive protein binding and radioimmunoassay data.

A computerized method has been developed and tested for the automatic computation of data obtained from competitive radio-binding assays, that is easily used by computer and non-computer oriented individuals. The program requires a series of only eleven parameter lines coded from the assay protocol, followed by the data exactly as it is produced from a standard sample counter. From the set of parameters the program is able to find standard curves at scattered locations through an assay, check their "log dose-logit response" least squares linear regression equations statistically for homogeneity of slopes and elevations, pool the standard curves and check the pooled least squares linear regression equation statistically for linearity and non-linearity. The results of the pooled standard curve is presented graphically and in tabular form. Using the linear equation for the pooled standard curves, the concentration for each unknown sample is predicted with its corresponding 95% confidence interval and presented in a table of unknowns. Also provided in the table of unknowns is a mean and standard error of the mean for all biological replicates, including footnote flags to warn the user when an unknown concentration: (i) is outside the 0-100% bound range; (ii) is estimated from a range outside that covered by the standards; or (iii) was estimated from the unusable tail regions of the standard curve.

Binding, Competitive↗
PubMed1986

Fertility and adaptation: Indochinese refugees in the United States.

"Levels of fertility among Indochinese refugees in the United States are explored in the context of a highly compressed demographic transition implicit in the move from high-fertility Southeast Asian societies to a low-fertility resettlement region. A theoretical model is developed to explain the effect on refugee fertility of social background characteristics, migration history and patterns of adaptation to a different economic and cultural environment controlling for marital history and length of residence in the U.S." The chief source for the data and analyses is the Indochinese Health and Adaptation Research Project (IHARP), San Diego State University. "Multiple regression techniques are used to test the model which was found to account for nearly half of the variation in refugee fertility levels in the United States. Fertility is much higher for all Indochinese ethnic groups than it is for American women; the number of children in refugee families is in turn a major determinant of welfare dependency. Adjustments for rates of natural increase indicate a total 1985 Indochinese population of over one million, making it one of the largest Asian-origin populations in the United States."

Acculturation↗
PubMedDate not supplied

Socio-economic variables influencing mean age at marriage in Karnataka and Kerala.

"In this paper an attempt was made to study the influence of certain socio-economic variables on the male and the female age at marriage in Karnataka and Kerala [India] for the year 1971. Step-wise regression method has been used to select the predictor variables influencing mean age at marriage. The results reveal that percent female literate...and percent female in labour force...are found to influence female mean age at marriage in Kerala, while the variables for Karnataka were percent female literate..., percent male literate..., and percent urban male population...."

Asia↗
PubMedDate not supplied

Secondary sex ratio variation during stressful times: the impact of the French revolutionary wars on a German parish (1787-1802).

The observation that declines in the human secondary sex ratio (SSR) may be linked to stressful periconceptional periods has received considerable attention (Catalano [2003] Hum Reprod 18:1972-1975; Catalano et al. [2005] Int J Epidemiol 34:944-948, [2005] Hum Reprod 20:1221-1227, [2005] Paediatr Perinat Epidemiol 19:413-420). For the purpose of testing the external validity of this phenomenon, birth records from four German village genealogies (N = 1,048) were analyzed to study the impact of the French Revolutionary Wars (1787-1802) on the proportion of male births. All births were subdivided into three cohorts (prewar, 1787-1792; war, 1792-1797; and postwar, 1797-1802). Differences in SSR between cohorts achieved statistical significance (chi2= 7.695; df = 2; P = 0.021). In addition, changes in SSR before, during, and after the wars were monitored by risk analysis. Using the SSR of the prewar period as a control, the results of the war cohort failed to achieve statistical significance (regression coefficient, -0.257; ExpB= 0.773; P = 0.118), while the odds reduction of 32.3% in the postwar period proved to be statistically significant (regression coefficient, -0.390; ExpB= 0.677; P = 0.006). It is hypothesized that the experience of postwar economic hardship (attributable to lowered food availability paired with dietary changes) represents the most likely proximate cause. The study also finds evidence of a parental sex ratio manipulation strategy meant to offset the female-biased SSR after the wars. It is argued that from an evolutionary perspective both the decline in SSR in response to stress as well as parental manipulation of the tertiary sex ratio convey reproductive advantages.

Birth Rate↗
PubMed2006

[Correlation and regression].

Correlation and regression are statistical methods that help us determine interactions of variables. Both are being used in statistical analysis of basic and clinical research. Correlation (r) is a measure of linear relationship between two numerical measurements made on the same set of subjects and it is represented by correlation coefficient. Values of correlation coefficient range between -1 and 1. Pearson's and Spearman's coefficients of correlation are the most often used correlation coefficients. Correlation can be linear and non-linear. We calculate the significance of correlation (P) in an effort to determine significance of correlation coefficient. Regression is a statistical method that allows us to predict values of one variable from another. The simplest regression is linear regression. The success of regression equation is valued by analysis of residuals. Multiple regression is used to predict one variable from several known variables.

Factor Analysis, Statistical↗
PubMed1983

A time series analysis of Swedish illegitimacy rates, 1911-1974.

Using a sociodemographic model of the determinants of illegitimacy rates, a multivariate regression analysis of annual change in age-specific Swedish illegitimacy rates is applied to the 1911-74 period. The proxy measure of change in sexual activity was significant for all age groups. Legitimation rates for out-of-wedlock conceived births were significant for all ages except teenagers, and the final predictor, women's status, was significant for all ages except women 35-44. Explained variance for annual change was highest among ages 20-24 (66%), 25-29 (66%), and 30-34 (63%) and lower among teens (34%) and women 35-44 (47%). These results support earlier research that used a sociodemographic model to explain post-World War II change in cross-national illegitimacy rates among 23 developed countries.

Adolescent↗
PubMed1984

Recent evidence on the effect of real earnings on net migration.

"This paper examines the effect of gross nominal earnings, gross real earnings, and net real earnings on net migration in a simultaneous-equation model of net migration and employment growth. Using US SMSA data for 1970-75, the study shows that nominal earnings are not a good proxy for real earnings. In addition, gross real earnings performed better than net real earnings, suggesting a possibility of 'tax illusion' on the part of the migrants. Besides, employment growth had a significant positive effect on net migration, whereas net migration affected employment growth positively but less significantly." (summary in FRE, GER)

Americas↗
PubMed2006

Amount and intensity of physical activity, fitness, and serum lipids in pre-menopausal women.

The aim of the study was to determine the association between the amount and the intensity of physical activity (PA) and lipid profile and fitness in pre-menopausal women. A cross-sectional study was conducted, sampling was stratified according to two age groups and two levels of PA, as assessed by the Minnesota Leisure Time PA Questionnaire. Serum lipid profile and sex hormones were measured. The study included 403 women. Total energy expenditure on PA was directly associated with HDL-cholesterol and inversely with atherogenic index. When intensity was analyzed, only moderate PA was associated with a desirable lipid profile. A decrease of 1.59 mg/dL (standard error [SE] = 0.77) and 0.07 units (SE = 0.02) in LDL-cholesterol and atherogenic index, respectively, and an increase of 1.02 mg/dL (SE = 0.34) in HDL-cholesterol were observed per each 100 MET . min/day spent in moderate PA. After adjusting for body fat mass, the association between moderate PA and LDL-cholesterol was no longer statistically significant (regression coefficient = - 1.21; SE = 0.81) whereas the association between moderate PA and atherogenic index (regression coefficient = - 0.05; SE = 0.02) and HDL-cholesterol (regression coefficient = 0.98; SE = 0.35) remained statistically significant. Only vigorous PA was associated with VO2max. VO2max increased 2.35 mL/kg (SE = 0.39) per each 100 MET . min/day spent in vigorous PA. Only moderate PA is associated with a lower LDL-cholesterol and atherogenic index, and higher HDL-cholesterol. The association between PA and LDL is dependent on body fat mass, but the association between PA and HDL is independent of it. Only vigorous intensity PA is associated with fitness.

Adolescent↗
PubMed2003

Relationship between nuclear morphometry, DNA content and resectability of pancreatic cancer.

AIM: To investigate the association of nuclear morphometry and DNA content with resectability of pancreatic cancer. METHODS: A total of 36 patients with pancreatic adenocarcinoma were divided into resectable group and unresectable group. The nuclear morphometry and DNA contents of tumor cells were analyzed by IBAS autoimagine analyzer from paraffin-embedded materials. Localization size, histological type and grade, and clinical stage of the tumor were evaluated. Factors influencing resectability of pancreatic cancer were investigated using stepwise regression analysis. RESULTS: Statistical significance was found in nuclear DNA content (integrated optical density, IOD) of tumor cells (1.64+/-0.41 vs 2.96+/-0.55), DNA ploidy, ages (46.5+/-5.3 years vs 58.6+/-0.7 years) and tumor volumes (298.1+/-101.5 cm(3) vs 634.7+/-512.5 cm(3)) in both groups (P<0.05), and no difference was found in the nuclear morphometry (P>0.05). The rates of diploid/tetraploid and aneuploid were 66.7 % and 33.3 % in resectable group respectively, and 38.9 % and 62.1 % in unresectable group, respectively (P<0.05). IOD (X(12)), ploidy status (X(12)) and clinical stage (X(3)) were radical resectable indicators with statistical significance. The regression equation for resectability was Y=-9.2053+3.5428X(12)+2.5390X(13)-2.3001X(3) (RR=0.8780, P<0.01). CONCLUSION: There is a high correlation between resectability of pancreatic cancers and their DNA contents, DNA ploidy status and clinical stage.

Adenocarcinoma↗
PubMed1991

Backcalculation of flexible linear models of the human immunodeficiency virus infection curve.

The authors present a regression approach to the backcalculation of flexible linear models of the HIV infection curve. They note that "because expected AIDS incidence can be expressed as a linear function of unknown parameters, regression methods may be used to obtain parameter and covariance estimates for a variety of interesting quantities, such as the expected number of people infected in previous time intervals and the projected AIDS incidence in future time intervals. We exploit these ideas to show that estimates based on maximum likelihood are, for practical purposes, equivalent to approximate estimates based on quasi-likelihood and on Poisson regression. These algorithms are readily implemented on a personal computer." These concepts are illustrated by projecting AIDS incidence in the United States up to 1993.

Acquired Immunodeficiency Syndrome↗