Levels of significance of some two-sample tests wkem observations are from compound normal distributions

This paper presents an investigation of the behavior of the levels of significance of the two-sample t and its related tests and the Mann-Whitney test when the samples are randomly drawn from mixtures of two normal populations (compound normals) and when the sample sizes are small (combined sample sizes ? 15). The use of the compound normal allows for investigation when the underlying populations are unequal, nonnormal, heterogeneous in variances, unimodal or bimodal, possessing smaller than normal kurtosis or containing contamination. The exact distribution of the t and its related tests are given. However, they are not readily amenable to calculations. Most of the numerical results presented were obtained by simulations     

American education: the challenge of change

The American education system is being challenged to raise the academic achievement of students to prepare them for the jobs of the future. Yet many demographic, as well as economic and social factors, are making the task more difficult. Low birth rates, especially among non-Hispanic whites, along with high immigration rates, have increased the share of minority and non-English students in public schools. The rise in single-parent families has increased the number of poor students and migration from the cities to the suburbs has concentrated poor and minority students in inner city schools. These same children will make up a greater share of the future labor force. At the same time, the aging of the general population may lessen the commitment of homeowners- -whose taxes pay between 1/3 and 1/2 of education costs. The aging labor force may bring a shortage of qualified teachers, particularly in specialized subject areas. Poor and minority students generally have below average academic skills and are more likely to drop out of high school than non-minority students. However, the skills of American students rank below those of most other industrialized nations, calling into question the ability of Americans to succeed in an increasingly international economic system. How can schools be improved and minority student achievement be enhanced? Reforms of education finance systems, court-ordered integration, and stiffer requirements for teachers and for graduation from high school are among many attempts to meet the immense challenges faced by American schools.     

A revised methodology for estimating total personal giving in the United States,with preliminary estimates for the period 1984–1992

This article describes a revised methodology for estimating the current amount of total personal giving in the United States. The previous methodology is evaluated and it is determined that a different methodology, drawing upon recent enrichments in the data on personal giving, would yield improved historical estimates. This would lead to more reliable extrapolations of the current level of giving. Preliminary historical estimates using the new methodology are made for the period 1984 through 1991. These serve as the base for extrapolations to 1992, and results using several extrapolation formulas are compared.The following changes are included in the historical estimates. Changes in the standard deduction strongly affect the decision to itemise deductions and contributions for a large and varying number of habitual contributors. Accordingly, two groups of contributions itemisers — permanent and transitory — were identified and their contributions separately estimated. The estimate of total giving now reflects the different income and contributions levels of each group. Tax return filers who can be taken as dependents on other persons' tax returns (predominantly children of living parents) are excluded from the group of non-itemiser returns. Tax return data on itemised contributions are adjusted using IRS tax return audit findings. A survey-based estimate of the proportion of non-contributos (zero contributors) is used to provide a more accurate count of the number of individuals and families who habitually make contributions but do not itemise them. An estimate is included of the contributions of the large number of low-income individuals and families not in the tax return data as they are not required to file tax returns.The research reported here has received financial support from the American Association of Fund-Raising Counsel Trust for Philanthropy     

European Communication Monitor: Current developments,issues and tendencies of the professional practice of public relations in Europe

The European Communication Monitor (ECM) research explores the current developments for communications disciplines, practices and instruments. It is an extensive research project to monitor trends in communication management, analyse the changing framework for the profession driven by European integration and evaluate specific topics of relevance to public relations practice. Specifically, the 2008 ECM edition is focused on aspects such as: strategy and control, interactive channels, corporate social responsibility, intercultural challenges, influence on management decision making, cooperation with agencies, and future budgets.