The Moment-Generating Function and Negative Integer Moments

It does not appear to be widely known that the moment-generating function M_x (t) contains information about negative as well as positive integer moments. Proofs of this are provided, extensions are indicated, and earlier literature deriving and using this type of result is briefly noted. Some examples are given.     

Student supervision

In October 1967 Sydney was the venue for the Annual Conference of The Australian Group for the Scientific Study of Mental Deficiency, the theme being “Preparing the Mentally Retarded for Adult Life”. A small group of students under the supervision of Mary McLelland¹ of Sydney University undertook a pilot study of the problems of the adolescent retarded, and the results of this were reported by her at a session of the conference. The subject was chosen because of direct and indirect pleas for help from parents of adolescent retarded people, mainly through the organization known as Aid Retarded Persons. Discussions and talks had taken place over a couple of years, and it is of this pre-conference thinking I am now writing. Parts of the material were given in talks to the parents and to a special group of the A.M.A.     

The Power of Imagination in Transnational Mobilities

At the roots of many travels to distant destinations, whether in the context of tourism or migration, are historically laden and socioculturally constructed imaginaries. People worldwide rely on such imaginaries, from the most spectacular fantasies to the most mundane reveries, to shape identities of themselves and others. These unspoken representational assemblages are powerful because they enact and construct peoples and places, implying multiple, often conflicting, representations of Otherness, and questioning several core values multicultural societies hold, by blurring as well as enforcing traditional territorial, social, and cultural boundaries. What are the contours of power, agency, and subjectivity in imaginaries of transnational mobility and the intersecting social categories those visions both reify and dissolve? Ethnographic studies of human (im)mobility provide an innovative means to grasp the complexity of the global circulation of people and the world-making images and ideas surrounding these movements. As a polymorphic concept, mobility invites us to renew our theorizing, especially regarding conventional themes such as culture, identity, and transnational relationships. This article critically analyzes some preliminary findings of an ongoing multisited research project that traces how prevalent imaginaries of transnational tourism to and migration from the “global South” are (dis)connected. I suggest anthropology has unique contributions to make to the current debate in the social sciences by ethnographically detailing how mobility is a contested ideological construct involving so much more than mere movement.     

Examining Organizational Functioning Through the Lens of Complexity Theory Using System Dynamics Modeling

ABSTRACT

The methodologies associated with complexity theory might serve as an adjunct to some of our more traditional behavioral social science research methods. While the latter has a well-established history in social work, the approaches related to complexity theory are just now gaining a foothold. One such approach is system dynamics modeling. This article will describe the application of system dynamics modeling to a well-known early intervention program. The manner in which it complements traditional research approaches will be discussed, and its unique contribution to understanding the organizational aspects of complexity theory will be highlighted.     

The Symmetry Rule: A Seven‐Year Study of Symptoms and Explanatory Labels Among Gulf War Veterans

Noticing medical symptoms can cause one to search for explanatory labels such as “ate bad food” or even “exposed to anthrax,” and perhaps these labels may cause new symptom reports. The present study examined whether there is empirical support for this symptom‐label “symmetry rule.” We interviewed veterans (N= 362) from the Gulf War Registry in 1995 and 2002 about their medical symptoms and about their exposure to war‐related hazards and stressors. Health symptom reports were strongly correlated between the two time periods and showed relatively stable mean levels, whereas recall of war‐related exposures was notably unstable. Veterans starting with fewer medical symptoms recalled fewer war‐related exposures seven years later. Initial recollection of chemical and biological warfare exposure (but not other exposures) longitudinally predicted novel medical symptoms. The findings generally support the symmetry rule hypotheses, although the evidence for the label to symptom link was less strong. The findings account for some variability in symptoms and exposure recall over time, but they do not, on their own, account for the Gulf War veterans' elevated number of unexplained medical symptoms.     

Educational objectives and measurement of outcomes

Correlation and regression analysis are often used to infer causal relationships in dynamic systems, even though computed on cross-sectional static data. In education these analytic techniques have been used to support assertions that school-controlled variables make little contribution to student learning. Critics of these assertions point to the low quality of the data, but it may be that the techniques themselves are inappropriate for the development of inferences of causality. This study simulated four possible models of dynamic relationships between family and school inputs and achievement outcomes. The models were run for five periods. Data generated were submitted to correlation and regression analysis. Both unique variance and regression coefficient indicators failed to describe reliably causal relationships built into the models. Conclusion: complex systems resist simplistic analyses.