In dispraise of the exact test: Do the marginal totals of the 2X2 table contain relevant information respecting the table proportions?

The use of the “exact test” with the 2X2 table that records the observations obtained in a comparative trial has been widely considered to be the paradigm of statistical tests of significance. This is attributable to the fact that it is based on the theories of R.A. Fisher and as a result has acquired the sobriquet ‘exact’.The Fisherian basis of the exact test, that the marginal totals are “ancillary statistics,” and therefore provide no information respecting the configuration of the body of the table is shown to be incorrect.The exact test for the one-sided case is compared with the normal test for the nominal significance levels P=0.05 and P=0.01. It is shown by direct computation that the effective level is closer to the nominal level with the normal test than with the exact test, and that the power of the normal test is considerably larger than the power of the exact test, the increased power exceeding the change of effective level.It is concluded that the exact test should not be used in preference to the normal test.     

Some generalizations of p1: External constraints,interactions and non-binary relations

In 1977, Holland and Leinhardt introduced a new statistical approach to sociometric data analysis. The details of their approach, based on a model termed P₁, were published in 1981 in papers by Holland and Leinhardt, and Fienberg and Wasserman. Since then, many researchers have adopted this model, addressing substantive questions that were unanswerable with existing methodology. The continuing methodological research of Fienberg and Wasserman has allowed this approach to be applied to many different types of sociometric data. We carry on this research by extending p₁ to three new situations: networks of such size that it is impossible for every actor to have contact or knowledge of the other actors; networks in which actor interaction can not be adequately modeled by the simple additive main effects of expansiveness and popularity; and networks in which we measure the strength of the relationship between actors using a non-binary or multivalued relational quantity.     

Properties of occurrence-exposure rate processes in multiple decrement theory

In a basic multiple decrement model empirical occurrence-exposure rates are defined for each of k risks to which a cohort from an animal or human population is exposed over a time interval. These rates are viewed as the evolution of a stochastic process. Some asymptotic properties of this process are considered. Weak convergence of the process and its uniform strong convergence are shown under mild conditions.     

Work stressors and cardiovascular disease

Over the past 20 years, an extensive body of research evidence has documented that psychosocial work stressors are risk factors for hypertension and cardiovascular disease. These stressors, which appear to be increasing in prevalence, include job strain (the combination of psychological job demands and low job control), imbalance between job efforts and rewards, threat-avoidant vigilant work, and long work hours. This article reviews the evidence linking these stressors with hypertension and CVD, and the physiological and social psychological mechanisms underlying the associations. Also described are methods for measuring work stressors and new, more accurate techniques for measuring blood pressure. Finally, strategies for reducing work stressors and preventing hypertension and CVD are reviewed. These include clinical assessment, worksite health promotion, work organization interventions, legal approaches and work site surveillance.     

Pathway Analysis for Population-Total Health Impacts of Toxic Metal Emissions

This article describes a simple model for quantifying the health impacts of toxic metal emissions. In contrast to most traditional models it calculates the expectation value of the total damage (summed over the total population and over all time) for typical emission sites, rather than "worst-case" estimates for specific sites or episodes. Such a model is needed for the evaluation of many environmental policy measures, e.g., the optimal level of pollution taxes or emission limits. Based on the methodology that has been developed by USEPA for the assessment of multimedia pathways, the equations and parameters are assembled for the assessment of As, Cd, Cr, Hg, Ni, and Pb, and some typical results are presented (the dose from seafood is not included and for Hg the results are extremely uncertain); the model is freely available on the web. The structure of the model is very simple because, as we show, if the parameters can be approximated by time-independent constants (the case for the USEPA methodology), the total impacts can be calculated with steady-state models even though the environment is never in steady state. The collective ingestion dose is found to be roughly 2 orders of magnitude larger than the collective dose via inhalation. The uncertainties are large, easily an order of magnitude, the main uncertainties arising from the parameter values of the model, in particular the transfer factors. Using linearized dose-response functions, estimates are provided for cancers due to As, Cd, Cr, and Ni as well as IQ loss due to Pb emissions in Europe.     

Systemic Uptake and Clearance of Chloroform by Hairless Rats Following Dermal Exposure. I. Brief Exposure to Aqueous Solutions

The systemic uptake of chloroform from dilute aqueous solutions into live hairless rats under conditions simulating dermal environmental exposure was studied. Whole blood was sampled during a 30-min immersion of an animal within water containing a known concentration of chloroform and then for 5.5 h following its removal from the bath. The amount of chloroform systemically absorbed was determined by comparing the AUCs of the blood concentration vs. time plots from dermal exposure to that obtained after IV infusion (for a period of 30 min) of an aqueous solution containing a known amount of chloroform (positive control). Although dermal data implied two-compartment disposition characteristics, IV infusion data fit best to a three-compartment disposition. Linear pharmacokinetics was observed both by IV administration and percutaneous absorption at the dose levels studied. Chloroform was detected in the rat blood as early as 4 min following exposure. Our findings suggest that about 10.2 mg of chloroform was systemically absorbed after dermal exposure of a rat to an aqueous solution of 0.44 mg/ml. This amount is substantially higher than the predictions of mathematical risk-models put forth by some investigators. However, when expressed as the "effective" permeability coefficient ( K _p^eff), close agreement was noticed between our value and those estimated by others using physiologically based pharmacokinetic (PBPK) models. Also, in terms of K _p^eff, reasonable agreement existed between our and another investigator's past estimates of uptake based on depletion of bath level of chloroform and the actual uptake measured in our current experiments. The estimated onset of systemic entry seen here is entirely consistent with our estimate of how long it takes to establish the diffusion gradient across the stratum comeum based on tape stripping.     

Type Methodology and Type Myth: Some Antecedents of Max Weber's Approach*

The methodological proposals of Windelband, Knies, Schmoller, Menger, Simmel, Dilthey and Rickert are surveyed and compared. Two difficulties in the writings are identified: the strict division which is urged (or accepted) between science and history, and the tendency to treat societies as “social wholes,” which have an autonomous existence and are self-developing.     

Critical review of the concept of the borderline child

The concept of the borderline child is reviewed in this paper. Questions are raised about the generally held assumption that a similarity exists between the dynamics of borderline children and those of borderline adults. It is suggested that no data is currently available to substantiate such a view. Further questions are raised about the assumption that the etiology of the disorder in childhood is based on poor or improper nurturance. A working definition of the concept of the borderline child is proposed that is free of preconceptions as to the etiology of the dysfunction. A hypothesis is presented for further investigation that at least some borderline children's etiology may be found in the presence of a minimal brain dysfunction or a severe learning disability.