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831.
832.
The results of a computer search for saturated designs for 2n factorial experiments with n runs is reported, (where n = 2 mod 4). A complete search of the design space is avoided by focussing on designs constructed from cyclic generators. A method of searching quickly for the best generators is given. The resulting designs are as good as, and sometimes better than, designs obtained via search algorithms reported in the literature. The addition of a further factor having three levels is also considered. Here, too, a complete search is avoided by restricting attention to the most efficient part of the design space under p-efficiency.  相似文献   
833.
Alternative ways of using Monte Carlo methods to implement a Cox-type test for separate families of hypotheses are considered. Monte Carlo experiments are designed to compare the finite sample performances of Pesaran and Pesaran's test, a RESET test, and two Monte Carlo hypothesis test procedures. One of the Monte Carlo tests is based on the distribution of the log-likelihood ratio and the other is based on an asymptotically pivotal statistic. The Monte Carlo results provide strong evidence that the size of the Pesaran and Pesaran test is generally incorrect, except for very large sample sizes. The RESET test has lower power than the other tests. The two Monte Carlo tests perform equally well for all sample sizes and are both clearly preferred to the Pesaran and Pesaran test, even in large samples. Since the Monte Carlo test based on the log-likelihood ratio is the simplest to calculate, we recommend using it.  相似文献   
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836.
Drawing from Sorokin's hypothesis that socially mobile individuals are at greater risk of experiencing psychological distress than their non-mobile counterparts, we investigate whether intergenerational occupational mobility influences psychological distress, as measured by the Center for Epidemiologic Studies Depression (CES-D) scale. Using data for men from the Wisconsin Longitudinal Study (WLS) and Sobel's Diagonal Mobility Models, we find little evidence for Sorokin's hypothesis; mobile individuals are no more likely to be psychologically distressed than their non-mobile counterparts. In fact, one group of mobile men - those who left their farming origins - are actually less distressed than the sons who remain as farmers and non-mobile men in higher-ranked social classes. We speculate that this reflects the fact that farming became very arduous during the late 20th century and these mobile sons of farmers appreciate their improved life chances. Our findings suggest that the association between mobility and psychological distress varies across specific class backgrounds and is contingent upon the broader social and economic context.  相似文献   
837.
In an investigation of students' potential biases toward gay and lesbian instructors, 93 female and 59 male undergraduates viewed a lecture, rated the instructor and perceived learning, and completed a lecture-retention test. Lectures were given by a man or woman, identified as straight or gay or lesbian. Sexual orientation did not affect the instructor evaluation or perceived learning ratings for any of the groups. Although sexual orientation did not affect the lecture-retention scores for the female students, learning by the male students was significantly lower with the gay male instructor than with the straight male instructor (p = .03), suggesting an implicit bias.  相似文献   
838.
This study examines adolescent depressive symptoms and the quantity and quality of time spent by adolescents with their parents and siblings. We use measures of the quality of relationships with parents and siblings as proxy indicators for the quality of time spent with these social partners. The study emphasizes the salience of parent relationships to adolescent depression. The structural equation models suggest that time spent with parents is indirectly linked with the severity of depressive symptoms via adolescents’ perceptions of how accepting their parents are of them, and the extent to which parents avoid exerting psychological control. We discuss these findings in relation to clinical practice.  相似文献   
839.
Self-esteem is linked to high-risk behaviors in other populations but has not been examined in women aged 50 and older. This study explored how self-esteem is related to variables that can influence high-risk sexual behaviors in women over 50. A multiethnic community-based sample of 572 women aged 50 and older completed an anonymous questionnaire on sexual behaviors, sociodemographic characteristics, and psychosocial measures relevant to midlife and older women. Regression analysis showed sensation-seeking, HIV stigma, sexual assertiveness, and self-silencing predicted self-esteem in women over 50 (F = 43.632, p < .001). Factors such as relational context, interpersonal power, and silencing can affect self-esteem and may be contributing to HIV risk in this group.  相似文献   
840.
Price and design quality define value for customers and are often used by firms to position products in the marketplace. Setting price and quality level on a new product for the first time and making appropriate changes over time to these variables to reflect changing conditions in the market requires careful coordination of design, manufacturing, and marketing variables. We present a control theoretic model to study the complex interaction among price, quality, and cost during the life cycle of a product. Our model considers the major design-manufacturing-marketing tradeoffs and helps determine optimal pricing, design quality, and production strategies in a dynamic environment with convex production costs.  相似文献   
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