World Population Growth; Past, Present and Future

Past, current and projected future population growth is outlined. Barring a calamitous pandemic, a further increase in the world’s population from 7 to between 8.8 and 10 billion by mid-century is unavoidable. This increase is driven by high fertility in sub-Saharan Africa whose population is forecast to more than double in the next 40 years and by a modest rise of 23 % in Asia’s huge population. Beyond mid-century, the range of plausible demographic destinations widens; much depends on fertility rates in the next few decades because they will determine the number of potential reproducers in the second half of the century. Vigorous promotion of family planning, particularly in Africa, is crucial to achievement of population stabilisation. Unchanged fertility implies a global population of 25 billion by the end of the century. In the next few decades the contribution of human population growth to global environmental change is moderate, because nearly all growth will occur in poor countries where consumption and emission of greenhouse gases is low. The implications for food production, and thereby water consumption, are greater. Much of the future need for food will be driven by increased numbers rather than changing diets. Loss of bio-diversity and natural habitats, degradation of fragile eco-systems due to over-exploitation and aquifer deletion are likely consequences.     

The Cognitive and Emotional Components of Behavior Norms in Outdoor Recreation

Behavioral norms consist of two components: a cognitive component of obligation that is the memory repository of social standards, and an emotional component of sanctions that are the feelings and physiological states that result when actual behavior is consistent or not consistent with the obligation. This article analyzes the cognitive and emotional components of norms identified in three studies of behaviors (littering, controlling dogs while cross country skiing, and bikers and skaters warning when passing) in outdoor recreation settings. All three studies provide data on obligations to behave a particular way and internal and informal sanctions for correct or incorrect behavior. Obligations for all the behaviors were highly crystallized and were not statistically different. Internal sanctions were shame and guilt, and informal sanction was embarrassment. The intensity of the norms was determined by summing individuals' responses for shame, guilt, and embarrassment. The power and prevalence of the norms were determined by cross tabulating obligations by intensities. Intensity, power, and prevalence were very high for littering and failing to control your dog while cross country skiing, but were very low for skaters and bikers failing to warn when passing slower users on a multiple use trail. Measuring sanctions is shown to be critical to determining the intensity, power, and prevalence of behavioral norms. Suggestions are given for ways to include sanctions in studies of social and environmental condition norms.     

Some Teaching Techniques for High School Economics

In this article two high school economics teachers describe several teaching techniques that have proven successful in their school. The use of a team approach is briefly explained, and the importance of student motivation is stressed. Among the methods included are skits, plays, the use of video tapes, simulations and games, and the analysis of important economic problems. The means by which the instructors are evaluating their course are set forth, with evidence that the experience helps to destroy commonly held myths about economics and greatly improves student understanding of basic principles.     

美国医疗决策中的卫生技术评估

卫生技术评估（Health technology assessment，HTA）是对卫生保健技术应用所产生的短期与长期结果进行检验的一种政策研究形式。评估的内容包括安全性、有效性、患者自报结果、现实效果、成本和成本一效果以及社会、法律、伦理和政治影响等。     

TV viewing: application of a formal choice model

Choices of television programs is viewed as a process of deciding among a set of alternative goods with zero prices. A choice model can thus be based purely on individuals' preferences for various characteristics of a set of shows available, incorporating the option of not watching if all shows are too dissimilar to these desires. The shows are first grouped according to salient characteristics and a preferred value for each characteristic is estimated for each potential viewer. A perceived position of each show is similarly estimated and watching is shown to decline as similarity between preferred show and available alternatives declines. The choice model predicts show choice better than simpler models based on aggregate audience measures or on network loyalty, but the explanatory power is weak; some suggestions for improvement are made.     

New Methods for Forecasting Inflation,Applied to the US*

Models for the 12‐month‐ahead US rate of inflation, measured by the chain‐weighted consumer expenditure deflator, are estimated for 1974–98 and subsequent pseudo out‐of‐sample forecasting performance is examined. Alternative forecasting approaches for different information sets are compared with benchmark univariate autoregressive models, and substantial out‐performance is demonstrated including against Stock and Watson's unobserved components‐stochastic volatility model. Three key ingredients to the out‐performance are: including equilibrium correction component terms in relative prices; introducing nonlinearities to proxy state‐dependence in the inflation process and replacing the information criterion, commonly used in VARs to select lag length, with a ‘parsimonious longer lags’ parameterization. Forecast pooling or averaging also improves forecast performance.