Book Reviews

This article uses a Bayesian unit-root test in stochastic volatility models. The time series of interest is the volatility that is unobservable. The unit-root testing is based on the posterior odds ratio, which is approximated by Markov-chain Monte Carlo methods. Simulations show that the testing procedure is efficient for moderate sample size. The unit-root hypothesis is rejected in seven market indexes, and some evidence of nonstationarity is observed in the TWSI of Taiwan.     

Comparisons of imputation methods with application to assess factors associated with self efficacy of physical activity in breast cancer survivors

ABSTRACT

Missing data are commonly encountered in self-reported measurements and questionnaires. It is crucial to treat missing values using appropriate method to avoid bias and reduction of power. Various types of imputation methods exist, but it is not always clear which method is preferred for imputation of data with non-normal variables. In this paper, we compared four imputation methods: mean imputation, quantile imputation, multiple imputation, and quantile regression multiple imputation (QRMI), using both simulated and real data investigating factors affecting self-efficacy in breast cancer survivors. The results displayed an advantage of using multiple imputation, especially QRMI when data are not normal.     

Analysis of Linear Models with One Factor Having Both Fixed and Random Levels

ABSTRACT

A general theory for a case where a factor has both fixed and random effect levels is developed under one-way treatment structure model. Estimation procedures for the fixed effects and variance components are consider for the model. The testing of fixed effects is considered when the variance–covariance matrix is known and unknown. Confidence intervals for estimable functions and prediction intervals for predictable functions are constructed. The computational procedures are illustrated using data from an on-farm trial.     

The General Expressions for the Moments of the Stochastic Shrinkage Parameters of the Liu Type Estimator

ABSTRACT

One of the problems with the Liu estimator is the appropriate value for the unknown biasing parameter d. In this article we consider the optimum value for d and give upper bound for the expected value of the estimator of this biasing parameter. We also derive the general expressions for the moments of the stochastic shrinkage parameters of the Liu estimator and the generalized Liu estimator. Numerical calculations are carried out to illustrate the behavior of the mean and variance of the biasing parameter. Also, a numerical example is given to illustrate the effect of the biasing parameter d, on the mean square error of the Liu estimator.     

Spatial heterogeneity in drinking water sources in the Greater Accra Metropolitan Area (GAMA), Ghana

Population and Environment - Universal access to safe drinking water is essential to population health and well-being, as recognized in the Sustainable Development Goals (SDG). To develop targeted...     

Contact Theory Extended: The Effects of Prior Racial Contact on Current Social Ties

Objective . We address methodological limitations in tests of contact theory. Just as importantly, we extend its theoretical focus to behaviors. Linking insights from social and cognitive psychology with contact theory, we hypothesize that prior racial contact will have significant effects on the racial diversity of contemporary social ties. Methods . Using the 1999–2000 Lilly Survey of Attitudes and Social Networks, we conduct univariate and multivariate analyses to test our hypotheses. Results . Those who had experienced prior interracial contact in schools and neighborhoods were more likely, as adults, to have more racially diverse general social groups and friendship circles. They were more likely to attend multiracial as opposed to a uniracial religious congregations, and to be interracially married. In general, these findings applied not only to all Americans, but to whites, African Americans, and Hispanics separately. They did not apply to Asians. Conclusions . Contact theory can and should be extended, rendering it more fruitful for studying race relations. Except when groups are an extremely small percentage of the population, even limited prior contact in multiracial settings appears to have important effects on contemporary social ties. These findings have important policy implications.     

Social security in the USSR

Social security systems reflect the political and economic realities of their country. The history of the Soviet social security system lends support to this thesis. Its basic features were drawn during Stalin's forceful drive towards heavy industrialization and they remained pretty much the same over the years despite many changes, often of significant detail. It was a system financed by the state, providing earnings-related benefits to workers who fulfilled their work obligations and favouring those in the Communist Party, government and industry whose contribution was deemed to be most useful to the state and the economy. The absence of political freedom meant that open criticism of existing provisions was very difficult, while the emphasis of successive governments on defence and space exploration inevitably meant that state funds for social security suffered and with them the level and range of benefits. The collapse of the Soviet Union has resulted in widespread hardship among those relying on benefits and has created a situation where new social security systems are needed to reflect the new political and economic realities.     

The Parks of Vienna

In this cross-cultural and historical contrast to the American park style, we see an eighteenth-century Viennese park, the Prater. This park has long been a showcase for the panoply of Viennese popular culture (“To be Viennese has long meant to visit the Prater”), serving as a generous stage for the mixing of classes and cultures. Here was a crossroad where immigrants, travelers, ethnics and the lower echelons could observe and mingle with the middle and upper reaches of society; a living laboratory of acculturation to the life of a cosmopolitan city. Together with the Schoenbrunn Zoo and other mainstays of the recreational outing, the park also provides an early example of environmental awareness in a rapidly expanding area calling for a balance between urban growth and green space. These effects indicate that popular culture, even within the limited realm of entertainment such as the amusement park, carries more serious implications for social and environmental issues.