Association of educational level and child sex ratio in rural and urban India

Utilizing data from the Census of India, this study compared child sex ratio in rural and urban regions of India and analyzed whether the child sex ratio was associated with mother’s education level. The child sex ratios in the rural and urban regions throughout India were analyzed using the two-sample and paired Student’s t-test. Further, the Chi-square test for trend in binomial proportions was used to assess the association between child sex ratios and mother’s education levels in rural and urban areas. Analysis of the data showed that there was a significant difference between the child sex ratios in rural areas versus urban areas. In addition, the Chi-square test for trend showed that there was a significant association of the child sex ratio and the educational levels of their mothers. This trend occurred in both rural and urban areas.     

A role for transportation in Canada

Transportation planning today involves all modes—airways, railways, roadways, waterways, and pipelines. Even the transmission of electrical power may be considered as a mode of transportation. Moreover, transportation planning involves the economic, political, and social systems of a nation. This paper is an attempt to create an awareness of the vast importance and complexity of transportation planning, to define a potential role of transportation, and finally, to suggest ways and means of achieving transportation's possible role.     

Quantile Regression Methods for Longitudinal Data with Drop-outs: Application to CD4 Cell Counts of Patients Infected with the Human Immunodeficiency Virus

Patients infected with the human immunodeficiency virus (HIV) generally experience a decline in their CD4 cell count (a count of certain white blood cells). We describe the use of quantile regression methods to analyse longitudinal data on CD4 cell counts from 1300 patients who participated in clinical trials that compared two therapeutic treatments: zidovudine and didanosine. It is of scientific interest to determine any treatment differences in the CD4 cell counts over a short treatment period. However, the analysis of the CD4 data is complicated by drop-outs: patients with lower CD4 cell counts at the base-line appear more likely to drop out at later measurement occasions. Motivated by this example, we describe the use of `weighted' estimating equations in quantile regression models for longitudinal data with drop-outs. In particular, the conventional estimating equations for the quantile regression parameters are weighted inversely proportionally to the probability of drop-out. This approach requires the process generating the missing data to be estimable but makes no assumptions about the distribution of the responses other than those imposed by the quantile regression model. This method yields consistent estimates of the quantile regression parameters provided that the model for drop-out has been correctly specified. The methodology proposed is applied to the CD4 cell count data and the results are compared with those obtained from an `unweighted' analysis. These results demonstrate how an analysis that fails to account for drop-outs can mislead.     

An analysis of variance type test for comparing clusters of DNA sequences based on randomization test methodologies

SUMMARY A method for comparing groupings of DNA sequences is presented, which utilizes randomization test methods to assign significance levels to a test statistic defined in terms of the Hamming distance between two sequences. The method, which is intuitively motivated by the analysis of variance procedure, partitions the variation caused by differences between clusters from the variation attributable to differences at random base pair locations within clusers. Implementation issues are discussed, and an example of the application of the method is provided.     

Effects of Race and Sex on Work Group Cooperation Vs. Competition

This study examines whether differences in individualism-collectivism by race and sex result in differences in cooperation vs. competition. Expanding upon the earlier work of Cox et al., individual and group-level comparisons are made by race and sex. Exclusively examining race-based effects, Cox et al. had suggested that blacks display greater cooperation than do whites. Our findings concur; however, we are able to demonstrate this using a more complete group-level comparison. Given literature suggesting sex to be as relevant as race when administering work force diversity, we further expanded upon the earlier study by testing for such effects. While some previous research has suggested a tendency for women to behave more cooperatively than do men, our findings show that this is not necessarily the case. Specifically, this study demonstrates that sex decreases in importance, when controlling for race. Applications and suggestions for future research are presented.     

ARE AUTOMOBILE SAFETY REGULATIONS WORTH THE PRICE: EVIDENCE FROM USED CAR MARKETS

The value consumers place on automobile safety regulations can be determined by examining the instantaneous effects changes in these regulations have on used vehicle prices. If consumers value safety regulations more than their cost, used vehicle prices decrease in response to a change in safety regulations. If consumers place at least some value on the safety induced by safety regulations, a change in emission control regulations will have a greater positive impact on used automobile prices than a change in safety regulations. Empirical results strongly support the latter case and, surprisingly, offer some support for the former case. (JEL L51, L62)     

Eigenvalue—Free methods for computing the distribution of a quadratic form in normal variables

The traditional method for computing the distribution of a quadratic form in normal variables, Pr(v'Qv相似文献