A fitted test for the behrens-fisher problem

In 1975, Lee and Gurland proposed a solution to the Behrens-Fisher problem. It had excellent control of size and power and was relatively simple to use. However it requires extensive special tables. This article proposes a modification of this approach. It replaces the tables with easily computed functions of the sample sizes and a standard t table. Control of size and power are equivalent to that obtained by Lee and Gurland. Furthermore, the test is also compared with the Welch's approximate t test and shows better control of size, with similar power curves when sample sizes are at least four from each of the two normal populations.     

An Implementation of Protocol Analysis and the Silent Dog Method in the Area of Behavioral Safety

Recent research has demonstrated that conducting safety observations increases the safety performance of the observer. The purpose of this study was to help determine whether observers make self-verbalizations regarding their own safety performance and whether these reports are functionally related to safety performance. In order to answer these questions two experiments were conducted using both protocol analysis and the silent dog method. The objective of Experiment 1 was (a) to determine whether safety performance with continuous, concurrent talk-aloud procedures is functionally equivalent to safety performance without talk-aloud reports, and (b) to determine whether that safety performance is altered when participants are presented with a distracter task. The goal of Experiment 2 was to determine whether the safety-related verbalizations made by Experiment 1 participants were task-relevant and functionally related to safety performance. The results from both Experiments 1 and 2 provide support for the existence of a functional relationship between safety-related verbalizations and increases in safety performance.     

Duration Adjustment of Acute Exposure Guideline Level Values for Trichloroethylene Using a Physiologically-Based Pharmacokinetic Model

Acute Exposure Guideline Level (AEGL) recommendations are developed for 10-minute, 30-minute, 1-hour, 4-hours, and 8-hours exposure durations and are designated for three levels of severity: AEGL-1 represents concentrations above which acute exposures may cause noticeable discomfort including irritation; AEGL-2 represents concentrations above which acute exposure may cause irreversible health effects or impaired ability to escape; and AEGL-3 represents concentrations above which exposure may cause life-threatening health effects or death. The default procedure for setting AEGL values across durations when applicable data are unavailable involves estimation based on Haber's rule, which has an underlying assumption that cumulative exposure is the determinant of toxicity. For acute exposure to trichloroethylene (TCE), however, experimental data indicate that momentary tissue concentration, and not the cumulative amount of exposure, is important. We employed an alternative approach to duration adjustments in which a physiologically-based pharmacokinetic (PBPK) model was used to predict the arterial blood concentrations [TCE(a)] associated with adverse outcomes appropriate for AEGL-1, -2, or -3-level effects. The PBPK model was then used to estimate the atmospheric concentration that produces equivalent [TCE(a)] at each of the AEGL-specific exposure durations. This approach yielded [TCE(a)] values of 4.89 mg/l for AEGL-1, 18.7 mg/l for AEGL-2, and 310 mg/l for AEGL-3. Duration adjustments based on equivalent target tissue doses should provide similar degrees of toxicity protection at different exposure durations.     

Review Essay: Thinking Critically about West Indians,Culture, and Identity

Qualitative Sociology -     

Fertility of immigrant women in California

Conclusion In California there has been much discussion of immigration and its longterm effects on the State. This paper has explored the question of differential fertility between immigrants and native-born Californians. We know from the decennial censuses that the proportion of immigrants to total Californians has increased significantly over the past 20 years. In addition, the characteristics of the immigrants have changed over time. The CEB ratios developed from the census enumeration and compared to other measures of fertility do show that immigrant women have higher fertility than native-born. A more detailed look shows that the country of birth composition, as measured by race/ethnicity, explains most of this difference.     

Reasons for substance use continuation and discontinuation during pregnancy: A qualitative study

Background

Substance use during pregnancy is a major public health concern, stemming from potential physical and psychosocial harms to both the mother and child.

Discrimination and Quality of Life Among Marriage-Squeezed Men in Rural China: Unexpected Functions of Structural and Functional Social Support

Social Indicators Research - In rural China, marriage-squeezed men are more likely to experience discrimination than other males. Using data collected from Anhui Province in China on...