A note on the accuracy of fisher's approximation to the large sample variance of an intraclass correlationa

The adequacy of Fisher's approximation to the large sample variance of an intraclass correlation is investigated in the context of family studies. It is found that the approximation is highly accurate in samples of moderately large size (≧ 30 families), and can also be used for significance-testing under a broad range of circumstances. The exact sampling of distribution of the intraclass correlation coefficient is also derived.     

A simple alternative to the likelihood ratio test in a logistic discrimination problem

We consider the problem of hypothesis-testing under a logistic model with two dichotomous independent variables. In particular, we consider the case in which the coefficients β₁, and β₂ of these variables are known on an a priori basis to not be of opposite sign. For this situation we show that there exists a simple nonparametric altenative to the likelihood ratio test for testing H₀: β₁ = β₂ = 0 VS.H₁ at least one β₁ = 0. We find the asympotic relative efficiency of this test and show that it exceeds 0.90 under a wide range of conditions. We also given an example.     

The political ecology of disaster: An analysis of factors influencing U.S. tornado fatalities and injuries, 1998–2000

This study examines casualties from tornadoes in the United States between the years 1998 and 2000. A political model of human ecology (POET) was used to explore how the environment, technology, and social inequality influence rates of fatalities and injuries in two models. Data were drawn from four sources: John Hart's Severe Plot v2.0, National Weather Service (NWS) Warning Verification data, Storm Prediction Center (SPC) watch data, and tract-level census data. Negative binomial regression was used to analyze the causes of tornado fatalities and injuries. Independent variables (following POET) are classified in the following manner: population, organization, environment, and technology. Rural population, population density, and household size correspond to population; racial minorities and deprivation represent social organization; tornado area represents environment; and tornado watches and warnings, as well as mobile homes, correspond to technology. Findings suggest a strong relationship between the size of a tornado path and both fatalities and injuries, whereas other measures related to technology, population, and organization produce significant yet mixed results. Census tracts having larger populations of rural residents was, of the nonenvironmental factors, the most conclusive regarding its effects across the two models. The outcomes of analysis, although not entirely supportive of the model presented in this study, suggest to some degree that demographic and social factors play a role in vulnerability to tornadoes.     

The Relative Effectiveness of Procedures Commonly Used in Multiple Regression Analysis for Dealing with Missing Values

Expressions are derived for the bias and variance associated with procedures frequently used to estimate partial regression coefficients in a linear model having the two explanatory variables x ₁ and x ₂, with missing values on x ₂ only. The expressions are used to help gain insight into the relative effectiveness of these procedures for handling more complex patterns of missing data.     

Kyne–Donner Model of Authority’s Recommendation and Hurricane Evacuation Decisions: A Study of Hypothetical Hurricane Event in the Rio Grande Valley,Texas

Many previous studies identified factors influencing hurricane evacuation decisions by testing the protective action decision model (PADM). This study further examines factors that affect the trust in authority’s recommendation and evacuation decision-making in a proposed Kyne–Donner Model. The model provides an understanding of the predictive factors influencing evacuation decision-making through the mediating factor of trust in authority’s recommendation. This study takes advantage of the structural equation modeling method to simultaneously test multi-stages of the model. There are factors, namely, age, gender, education, household size, decision maker, risk area, house materials, hurricane evacuation experience, information seeking frequency, information seeking behavior, and information sources which influence trust in authority’s recommendation which, together with hurricane evacuation impediments, influence the hurricane evacuation decision. The study’s findings are consistent with the PADM and demonstrate the importance of trust in authority’s recommendation and hurricane evacuation decision-making.     

The impact of missing values in the concentration–time curve on the assessment of bioequivalence

A complication that may arise in some bioequivalence studies is that of ‘incomplete subject profiles’, caused by missing values that occur at one or more sampling points in the concentration–time curve for some study subjects. We assess the impact of incomplete subject profiles on the assessment of bioequivalence in a standard two‐period crossover design. The specific aim of the investigation is to assess the impact of four different patterns of missing concentration values on the coverage level of a 90% nominal two‐sided confidence interval for the ratio of geometric means and then to consider the impact on the probability of concluding bioequivalence. An overall conclusion from the results is that random missingness – that is, missingness for reasons unrelated to the bioavailability of the formulation involved or, more generally, to any aspect of the study design and conduct – has a damaging effect on the study conclusions only when the number of missing values is fairly large. On the other hand, a missingness pattern that potentially has a very damaging effect on the study conclusions is that which arises when values are missing ‘late’ in the concentration–time curve. Copyright © 2005 John Wiley & Sons, Ltd     

Assimilation and Localism: Some Very Small Towns in Mass Society

A major theme in social theory concerns the transformation of social relationships in small communities as a result of modernization. This paper examines changing social relations in some small towns in southeastern Pennsylvania. For several hundred years, the residents of these towns have continuously developed institutions to preserve their local identity and maintain personal relations at the same time that they are incorporated into larger, regional social systems. The same local institutions and relations, however, are replicated in each small town, suggesting that local and particular interests are expressed through regional institutions. Although focused on a few small towns in one region of the United States, this paper examines the local expression of processes which are global.