Statistical Issues in fMRI for Brain Imaging

Functional magnetic resonance imaging is a technique developed in the last decade and used in the fields of cognitive psychology and neuroscience, among others, to study the processes underlying the working of the human brain. In this paper we examine some of the statistical issues in functional magnetic resonance imaging for brain research. We start by giving a brief introduction to the physics of magnetic resonance imaging. Using a psychological experiment as a case study, we then describe questions of design and statistical analysis. The data obtained from functional magnetic resonance imaging studies are of a highly complex nature, displaying both spatial and temporal correlation, as well as high levels of noise from different sources. Given this, the scope for statistics is vast, and is not limited to simple analysis of the data, once collected.     

Slipping Anchor? Testing the Vignettes Approach to Identification and Correction of Reporting Heterogeneity

We propose tests of the two assumptions under which anchoring vignettes identify heterogeneity in reporting of categorical evaluations. Systematic variation in the perceived difference between any two vignette states is sufficient to reject vignette equivalence. Response consistency - the respondent uses the same response scale to evaluate the vignette and herself - is testable given sufficiently comprehensive objective indicators that independently identify response scales. Both assumptions are rejected for reporting of cognitive and physical functioning in a sample of older English individuals, although a weaker test resting on less stringent assumptions does not reject response consistency for cognition.     

Decision aid reliance: Modeling the effects of decision aid reliability and pressures to perform on reliance behavior

We investigate the effects of decision aid reliability and pressure to perform on decision aid reliance. A total of 403 students took part in a four (pressures to perform: one through four) by five (decision aid reliability: 50%, 60%, 70%, 80% and 90%) between-participants experiment. We test two competing models of decision aid reliance behavior: pressure-induced rationality and pressure arousal theory. Additionally, we introduce a general model of reliance on a decision aid. We find that pressure arousal theory predominantly explains decision aid reliance behavior at all but the highest level of decision aid reliability tested in this study (90%). Our results indicate that there are reliance peaks across the reliability levels as more pressure to perform is applied, and that continually increasing pressures can eventually lead to decreased, rather than increased, reliance.     

AN INTEGRATED ECONOMETRIC MODEL OF THE CANADIAN LIVESTOCK-FEED SECTOR*

Canadian econometric studies dealing with the livestock-feed sector have tended to concentrate on individual commodities, or on a particular component of the market equilibrium process. In this article an integrated model of the sector is presented which depicts the nature of commodity interactions both at the consumer level and the producer level. The feed sector was conceptualized primarily in terms of derived demand. The model contained a total of 82 equations, of which 64 were related to the livestock subsystem. The estimated model was subsequently used for predicting the impact of changes in selected instrumental variables on the livestock-feed sector.
Les dernières etudes économétriques canadiennes traitant du pâturage se sont concentrées sur les produits séparés on sur un composé particulier répondant au besoin commercial. Cet article présents un modèle intégré du secteur montrant la nature des actions réciproques entrc les produits au niveau du consommateur et du producteur. Le secteur pâturage est expliqué en fonction de la demande. Le modèle contenait 82 équations, 64 desquelles se rapportaient àľélevage; par conséquent le modèle est employé pour prédire ľinfluence dans les pâturages de changements opérés sur les composants choisis.     

Ethno-cultural diversity and organizational effectiveness: a field study

This paper examines the relationship between ethno-cultural diversity and attitudinal and non-attitudinal measures of organizational performance in a field setting. Data were collected from ninety-eight respondents in seven branches of a leading Canadian bank. As compared to culturally homogeneous branches, the culturally heterogeneous branches experienced lower levels of absenteeism and achieved higher productivity and financial profitability despite their lower scores on job satisfaction, organizational commitment and workplace coherence, and higher rates of turnover. These relationships were moderated by age, job tenure, organizational position, children's age, location of education and previous employment, birthplace and education level.     

Discriminating between alternative measures of over-education

Five over-education measures are evaluated empirically on the basis of encompassing tests. The measures are based on job analysis (JA), worker-assessment of the required level to do the job (WAd), worker-assessment of the required level to get the job (WAg), the mean educational level of realized matches (RMmn), and the modal level of realized matches (RMml). Over- and under-education are linked to wages, job satisfaction, mobility and training participation. For none of the outcome variables, the JA model is encompassed by another model. Given the risk on systematic errors, this is a sufficient condition to prefer a carefully conducted JA to any other measure. The most reliable solution is to use the JA measure as an instrument for the WAd measure.     

Growing richer and taller: Explaining change in the distribution of child nutritional status during Vietnam's economic boom

Over a five-year period in the 1990s Vietnam experienced annual economic growth of more than 8% and a 15 point decrease in the proportion of children chronically malnourished (stunted). We estimate the extent to which changes in the distribution of child nutritional status can be explained by changes in the level and distribution of income, and of other covariates. This is done using data from the 1993 and 1998 Vietnam Living Standards Surveys and a flexible decomposition technique based on quantile regression that explains change throughout the complete distribution of child height. One-half of the decrease in the proportion of children stunted is explained by changes in the distributions of covariates and 35% is explained by change in the distribution of income. Covariates, including income, explain less of the decrease in very severe malnutrition, which is largely attributable to change in the conditional distribution of child height.     

Sectoral determinants of foreign affiliate sales employing European data

We test theories on sectoral determinants of foreign affiliate sales employing European foreign affiliate sales statistics (FATS). On the one hand, we test hypotheses that foreign affiliate sales are less likely in sectors with complex tasks and more likely in sectors where communication with customers is important. On the other hand, we test the hypothesis that the force of gravity is stronger in more complex sectors. Employing Poisson and negative binomial estimators, we find support for the first hypotheses and contradict the second hypothesis. We show that the interaction effect between distance and complexity changes sign from negative to positive when complexity is included as a separate regressor. We propose an explanation to reconcile our findings with the basic assertion in the second hypothesis that the force of gravity is stronger in more complex sectors, based on a composition effect between horizontal and vertical affiliate sales.     

Corporations,minors, and other innocents — A reply to R. E. Ewin

R. E. Ewin has argued that corporations are moral persons, but Ewin describes them as being unable to think or to act in virtuous and vicious ways. Ewin thinks that their impoverished emotional life would not allow them to act in these ways. In this brief essay I want to challenge the idea that corporations cannot act virtuously. I begin by examining deficiencies in Ewin's notion of corporate personhood. I argue that he effectively reduces corporations to the status of incompetent patients. I shall make use of a richer notion of corporate personhood as I explore the logical relationship between corporate action and the quality of the corporate emotional life. After discussing an alternate methodology for making moral assessments of action I consider briefly two corporate disasters: the crash on Mt. Erebus, the Imperial Foods plant fire. These cases are used to show the inadequacy of Ewin's thesis that only corporate managers are capable of displaying vice.P. Eddy Wilson taught philosophy full time for two years after graduation at the University of the South and he was a participant in Peter French's 1990 NEH Summer Seminar. He is currently employed as a member of the Department of Philosophy and Religion of Shaw University to teach philosophy at their High Point CAPE Center in High Point, North Carolina. He is interested in philosophy of religion, process philosophy, and ethics. Two of his articles have been accepted for publication by theJournal of Social Philosophy.     

STOCK PRICE REACTIONS TO DIVIDEND AND EARNINGS ANNOUNCEMENTS: CONTEMPORANEOUS VERSUS NONCONTEMPORANEOUS ANNOUNCEMENTS

In this paper we examine stock price reactions to contemporaneous and noncontemporaneous dividend and earnings announcements. Overall, the stock price reaction to joint announcements is significantly greater than the reaction to just one signal. This implies that there is information content to two signals being given simultaneously, and that announcements are not perfect substitutes. Some evidence shows that the reaction to a joint announcement is approximately twice that to a noncontemporaneous announcement. On average, the stock price reaction to joint contradictory announcements is not significant. Finally, for joint announcements where only one of the two announcements is expected to affect the stock price significantly, the market reaction is determined by the nonzero signal.