多媒体辅助教学的优势及存在的问题

多媒体辅助教学与传统的教学模式相比,具有智能化、信息量大以及新颖性等优势。然而在实际多媒体课堂教学中还存在排斥传统的课堂教学模式,华而不实、容量过大、教师变成了放映员等问题。此外,针对上述问题提出几点建议。     

Domains of convergence for the EM algorithm: a cautionary tale in a location estimation problem

The EM algorithm is a popular method for maximizing a likelihood in the presence of incomplete data. When the likelihood has multiple local maxima, the parameter space can be partitioned into domains of convergence, one for each local maximum. In this paper we investigate these domains for the location family generated by the t-distribution. We show that, perhaps somewhat surprisingly, these domains need not be connected sets. As an extreme case we give an example of a domain which consists of an infinite union of disjoint open intervals. Thus the convergence behaviour of the EM algorithm can be quite sensitive to the starting point.     

DO DRINKERS KNOW WHEN TO SAY WHEN? AN EMPIRICAL ANALYSIS OF DRUNK DRIVING

This paper presents empirical evidence that an individual's decision to drive while drunk is negatively affected by the expected full price of driving drunk. The analysis uses a unique data set containing information on self-reported drunk driving matched to state-level drunk driving policies as well as to state excise taxes on beer. These are hypothesized and found to affect drunk driving. Further, we find interesting racial differences but surprisingly small differences by gender in the effect of socioeconomic and policy variables on drunk driving propensities.     

The Meaning of Work and Love: Career Issues and Interventions

Examining concepts about work and love can help people increase their career success and life satisfaction. Career counselors may initiate this examination by eliciting clients' concepts about work and love. After hearing a client's ideas about work and love, counselors can compare this personal meaning to the social meaning of work and love. When this comparison reveals dysfunctional beliefs about work and love, counselors can link these beliefs to their client's career concerns. Such a linkage typically provokes a cognitive dissonance that motivates clients to modify their beliefs. Counselors can facilitate meaning modification by using client-centered and social influence techniques.     

First Nations and community economic development: a case study

A training project in a northern Canadian community providedan opportunity to examine participatory planning approachesand the meaning of work in First Nations communities. Focusgroups conducted three years after the unsuccessful interventionof a community economic development (CED) project suggest thatcomplex factors such as lack of support from community leadersand rate of pay for workers determine whether CED is alwaysappropriate in northern, First Nations contexts.     

The Division of Household Labor in Germany and Israel

We compare the patterns of household division of labor in Germany and Israel—two countries that share key elements of the corporatist welfare regime but differ in their gender regimes—and evaluate several hypotheses using data from the 2002 International Social Survey Program. Although time constraints and relative resources affect the division of household labor and women’s housework in both societies, we find that in Germany the gender order of household labor is more rigid, whereas in Israel the spouses’ linked labor market status exerts distinctive effects. We also find significant relationships between gender ideology and the division of household labor. We discuss the theoretical advantages of approaching the comparative study of gender inequality from the vantage point of family and gender regimes.     

Analytical approximations for iterated bootstrap confidence intervals

Standard algorithms for the construction of iterated bootstrap confidence intervals are computationally very demanding, requiring nested levels of bootstrap resampling. We propose an alternative approach to constructing double bootstrap confidence intervals that involves replacing the inner level of resampling by an analytical approximation. This approximation is based on saddlepoint methods and a tail probability approximation of DiCiccio and Martin (1991). Our technique significantly reduces the computational expense of iterated bootstrap calculations. A formal algorithm for the construction of our approximate iterated bootstrap confidence intervals is presented, and some crucial practical issues arising in its implementation are discussed. Our procedure is illustrated in the case of constructing confidence intervals for ratios of means using both real and simulated data. We repeat an experiment of Schenker (1985) involving the construction of bootstrap confidence intervals for a variance and demonstrate that our technique makes feasible the construction of accurate bootstrap confidence intervals in that context. Finally, we investigate the use of our technique in a more complex setting, that of constructing confidence intervals for a correlation coefficient.