Evolution of an urban epidemic: The first 100,000 AIDS cases in New York City

Between 1981 and August 1997, 100,000 AIDS cases were reported in New York City (NYC): 77,067 men, 20,818 women, 307 teenagers, and 1,808 children. This report examines AIDS trends in NYC as the epidemic evolved from a predominantly white male epidemic among men with same sex contact (MSM) mostly from a single borough to a geographically diffuse epidemic that includes injecting drug users (IDU), persons of color, and women infected heterosexually. Case data were collected by active surveillance methods augmented by electronic laboratory based reporting. Mortality data were obtained from NYC Vital Statistics. 1990 Census data were used to derive incidence rates and prevalence by neighborhood income. Rates per 100,000 adults by neighborhood ranged from 260 to 5,500. Total AIDS incidence peaked in 1993 and has subsequently declined. Among men there was a shift from MSM to IDU as the predominant risk group, and increasing incidence among men reporting heterosexual contact. IDU was the leading risk factor among women, and women increased from 8 to 30 percent of all cases between 1982 and 1997. Unlike incidence, AIDS prevalence is rising among socially and economically marginalized populations, and will remain a major public health challenge well into the next century.     

An estimator of population total in multiple characteristics and its robustness to product moment correlation coefficient

We developed an alternative estimator for the probability proportional to size with replacement sampling scheme when certain characteristics under study have low correlation with the size measured used for sample selection. The performance of the proposed estimator has been studied with other related alternative estimators by comparing biases and the variances of respective alternative estimators. Most of the alternative estimators assume the knowledge of the product moment correlation coefficient. Therefore an empirical study, with the help of wide variety of populations, has been carried out to study their respective efficiency when correlation coefficient is departed from its true value.     

县级政府规模影响因素的实证研究——以四川省为例

以2007年四川省177个县级行政单位为样本,考察县级政府规模与经济发展水平、常住人口数量、管辖区域面积之间的相关关系。研究结果表明,经济发展水平、常住人口数量、管辖区域面积三大因素对县级政府规模存在不同程度的影响,充分考虑这些影响因素,可以为优化并确立合理的政府规模提供有价值的政策建议。     

A note on the asymptotic efficiency of the sobel–wald test

Let X₁,X₂, … be iid random variables with the pdf f(x,θ)=exp(θx?b(θ)) relative to a σ-finite measure μ, and consider the problem of deciding among three simple hypotheses H_i:θ=θ_i (1?i?3) subject to P(acceptH_i|θ_i)=1?α (1?i?3). A procedure similar to Sobel–Wald procedure is discussed and its asymptotic efficiency as compared with the best nonsequential test is obtained by finding the limit lim_a→0(E_iN(a)/n(a)), where N (a) is the stopping time of the proposed procedure and n(a) is the sample size of the best non-sequential test. It is shown that the same asymptotic limit holds for the original Sobel–Wald procedure. Specializing to N(θ,1) distribution it is found that lim_a→0$\text{(E}{}_{\mathrm{i}}\text{N(α)/n(α))=}\text{1}\text{4}$ (i=1,2) and lim_a→0 (E₃N(α)n(α))=δ²₁/4δ, where δ_i=(θ_i+1?θ_i) with 0<δ₁?δ₂. Also, the asymptotic efficiency evaluated when the X's have an exponential distribution.