Hypothesis testing, power and sample size determination for between group comparisons in fMRI experiments

Modern methods for imaging the human brain, such as functional magnetic resonance imaging (fMRI) present a range of challenging statistical problems. In this paper, we first develop a large sample based test for between group comparisons and use it to determine the necessary sample size in order to obtain a target power via simulation under various alternatives for a given pre-specified significance level. Both testing and sample size calculations are particularly critical for neuroscientists who use these new techniques, since each subject is expensive to image.     

The feminine side to Santa Claus. Women's work of kinship in contemporary gift-giving relations

The predominant male-breadwinner model having been surpassed by other forms of household organization, discussion rises on whether the female role of caretaker within households also undergoes change. The question certainly becomes relevant concerning an often less visible and/or overlooked aspect of the caretaker role, which is the ‘work of kinship’. This article looks at a specific aspect of this, which can be considered as even more invisible than other caring tasks: the responsibility for gift exchange. More precisely, we explore women's role in, contribution to and attitude towards the gift-giving process on three domains: the buying, giving and receiving of gifts. Results point to important gender differences: women remain chief responsible for gift selection and gift giving and invest more time in selecting the appropriate gifts for kin. They also show greater satisfaction with the gift-giving process, of which they tend to stress the symbolic value instead of the instrumental value, which is more strongly emphasized by men. This shows that traditional role models endure in an important but often invisible aspect of the work of kinship and more generally of the caretaker role and that these role models also seem to be strongly culturally integrated by men and women.     

Using the Summed Rank Cusum for monitoring environmental data from industrial processes

Environmental issues have become a hot topic recently, especially those surrounding industrial outputs. Effluents, emissions, outflows, by-products, waste materials, product de-commissioning, land reclamation and energy consumption are all the subject of monitoring, either under new legislation or through economic necessity. Many types of environmental data are often difficult to understand or measure because of their unusual distribution of values however. Standard methods of monitoring these data types often fail or are unwieldy. The scarcity of events, small volume measurements and the unusual time scales sometimes involved add to the complexity of the task. One recently developed monitoring technique is the Summed Rank Cusum (SRC) that applies non-parametric methods to a standard chart. The SRC can be used diagnostically and this paper describes the application of this new tool to three data sets, each derived from a different problem area. These are measuring industrial effluent, assessing the levels of potentially harmful proteins produced by an industrial process and industrial land reclamation in the face of harmful waste materials. The use of the SRC to spot change points in time retrospectively is described. The paper also shows the use of SRC in the significant-difference testing mode, which is applied via the use of spreadsheets. Links to other similar methods described in the literature are given and formulae describing the statistical nature of the transformation are shown. These practical demonstrations illustrate that the graphical interpretation of the method appears to help considerably in practice when trying to find time-series change points. The charts are an effective graphical retrospective monitoring technique when dealing with non-normal data. The method is easy to apply and may help considerably in dealing with environmental data in the industrial setting when standard methods are not appropriate. Further work is continuing on the more theoretical aspects of the method.     

Windows to the Soul? Deliberate Eye Contact as a Cue to Deceit

Although people overwhelmingly believe that liars avoid eye contact, meta-analyses of deception literature have shown a non-significant relationship between gaze and deception. In the present experiment we measured eye movements in an innovative way. We coded the extent to which interviewees deliberately made eye contact with the interviewer. Liars take their credibility less for granted than truth tellers. They therefore may have a greater desire to be convincing and hence more inclined to monitor the interviewer to determine whether they seem to be being believed. We therefore hypothesized that liars would give more appearance of deliberately making eye contact than truth tellers (a relationship which opposes the stereotypical belief that liars look away). A total of 338 passengers at an international airport told the truth or lied about their forthcoming trip. As well as the deliberate eye contact variable, we coded the amount of time the interviewees looked away from the interviewer (e.g., gaze aversion), which is typically examined in deception research. Liars displayed more deliberate eye contact than truth tellers, whereas the amount of gaze aversion did not differ between truth tellers and liars.     

Towards a sociology of transgendered bodies

The articulation of a generic social process of 'body femaling' presented in Ekins (1993) and elaborated in Ekins (1997) is further developed in this article to provide a conceptual framework for a sociology of trans-gendered bodies. Transgendering refers both to the idea of moving across (transferring) from one pre-existing gender category to another (either temporarily or permanently), and to the idea of transcending or living 'beyond gender' altogether. Following Plummer's (1995) work on sexual stories, we distinguish a number of contemporary transgendering body stories which we consider in terms of four major modes or styles of body transgendering: those we identify as 'migrating', 'oscillating', 'erasing' and 'transcending'. We give illustrative examples of each mode with reference to the binary male/female divide, the interrelations between sex, sexuality and gender, and the interrelations between the four main sub-processes of transgendering, which we identify as 'substituting', 'concealing', 'implying' and 'redefining'.     

MENTAL ILLNESS AND THE DEMAND FOR ALCOHOL, COCAINE, AND CIGARETTES

This article estimates the effect of mental illness on demand for addictive substances, allowing for structural endogeneity and simultaneity between mental illness and addictive consumption. Results show that individuals with a history of mental illness are 26% more likely to consume alcohol, 66% more likely to consume cocaine, and 89% more likely to consume cigarettes. This high-participation group is also price-responsive, although their price elasticities differ somewhat from those without mental illness. The results provide added justification for higher taxes and supply reduction activities. Furthermore, subsidizing the treatment of mental illness can reduce addictive consumption.(JEL I1 )     

Quality of College Life (QCL) of Students: Further Validation of a Measure of Well-being

This paper reports a study designed to further validate a measure of quality of college life (QCL) of university students (Sirgy, Grzeskowiak, Rahtz, Soc Indic Res 80(2), 343–360, 2007). Two studies were conducted: a replication study and an extension study. The replication study involved surveys of 10 different college campuses in different countries. The results of the replication study provided additional nomological (predictive) validation support of the measure based on a theoretical model mapping out the antecedents and consequences of satisfaction with college life. With respect to the extension study, the focus was to further test the nomological validity of the QCL measure by arguing and empirically demonstrating that the consequence of QCL is life satisfaction. The extension study involved a survey of three college campuses in different countries. The results were also supportive of the nomological validity of the QCL measure.     

Erratum to: Beyond the urban stream syndrome: organic matter budget for diagnostics and restoration of an impaired urban river

Urban Ecosystems - This article was unintentionally published twice in this journal, by the same authors.     

The dangers posed by saddle points, and other problems, when using central composite designs

This paper discusses two problems, which can occur when using central composite designs (CCDs), that are not generally covered in the literature but can lead to wrong decisions-and therefore incorrect models-if they are ignored. Most industrialbased experimental designs are sequential. This usually involves running as few initial tests as possible, while getting enough information as is needed to provide a reasonable approximation to reality (the screening stage). The CCD design strategy generally requires the running of a full or fractional factorial design (the cube or hypercube) with one or more additional centre points. The cube is augmented, if deemed necessary, by additional experiments known as star-points. The major problems highlighted here concern the decision to run the star points or not. If the difference between the average response at the centre of the design and the average of the cube results is significant, there is probably a need for one or more quadratic terms in the predictive model. If not, then a simpler model that includes only main effects and interactions is usually considered sufficient. This test for 'curvature' in a main effect will often fail if the design space contains or surrounds a saddle-point. Such a point may disguise the need for a quadratic term. This paper describes the occurrence of a real saddle-point from an industrial project and how this was overcome. The second problem occurs because the cube and star point portions of a CCD are sometimes run as orthogonal blocks. Indeed, theory would suggest that this is the correct procedure. However in the industrial context, where minimizing the total number of tests is at a premium, this can lead to designs with star points a long way from the cube. In such a situation, were the curvature test to be found non-significant, we could end with a model that predicted well within the cube portion of the design space but that would be unreliable in the balance of the total area of investigation. The paper discusses just such a design, one that disguised the real need for a quadratic term.