A Comparison of Heuristic Procedures for Minimum Within-Cluster Sums of Squares Partitioning

Perhaps the most common criterion for partitioning a data set is the minimization of the within-cluster sums of squared deviation from cluster centroids. Although optimal solution procedures for within-cluster sums of squares (WCSS) partitioning are computationally feasible for small data sets, heuristic procedures are required for most practical applications in the behavioral sciences. We compared the performances of nine prominent heuristic procedures for WCSS partitioning across 324 simulated data sets representative of a broad spectrum of test conditions. Performance comparisons focused on both percentage deviation from the “best-found” WCSS values, as well as recovery of true cluster structure. A real-coded genetic algorithm and variable neighborhood search heuristic were the most effective methods; however, a straightforward two-stage heuristic algorithm, HK-means, also yielded exceptional performance. A follow-up experiment using 13 empirical data sets from the clustering literature generally supported the results of the experiment using simulated data. Our findings have important implications for behavioral science researchers, whose theoretical conclusions could be adversely affected by poor algorithmic performances.     

Testing alternative explanations of phantom decoy effects

Phantom decoys are alternatives that asymmetrically dominate a targeted alternative and yet lead to increased selection of the target when the decoy is declared to be unavailable. This effect is difficult to explain within most standard theoretical accounts of decoy effects. The current experiments tested between three explanations of this effect: (1) the relative advantage model based on loss aversion, (2) similarity substitution, and (3) range weighting. In Experiment 1, participants were presented trinary choice sets, with half of the sets containing a phantom decoy in one of five possible locations within the attribute space. Phantom decoy effects were robust across all decoy locations but one, and the pattern of effects most closely corresponded to predictions of the relative advantage model. Experiment 2 used a within‐subjects manipulation of the five phantom decoy locations. The overall pattern of effects most closely corresponded to predictions from the relative advantage model, as did the pattern for the group of participants who exhibited the strongest phantom decoy effects. Copyright © 2007 John Wiley & Sons, Ltd.     

Satisfactions and Regrets of Midlife Parents: A Qualitative Analysis

The study examined the satisfactions and regrets of midlife parents at a specific family life-cycle milestone, their child’s graduation from high school. The purpose was to compare mothers’ and fathers’ appraisals of the gains and losses associated with this developmental transition and turning point in their parenting roles. A total of 260 parents (147 mothers; 113 fathers) who had a child graduating from high school responded in writing to open-ended questions regarding their satisfactions and regrets at this stage of their lives. Responses were coded to identify themes salient to these parents. Results indicate that both mothers and fathers are aware of both the gains and losses at this time in their family life cycle, but they differed in how they expect to be affected by the transition. Mothers’ responses suggest that they are anticipating and planning for the transition. Fathers’ responses suggest they are less aware of the personal implications of this family transition and are less prepared for its emotional impact.     

Modeling the Ecological Validity of Neurocognitive Assessment in Adults with Acquired Brain Injury

Neuropsychologists are increasingly asked to make judgments regarding treatment options and rehabilitation strategies in addition to evaluating the degree and scope of neuropsychological impairment following acquired brain injuries. The capacity to make informed clinical decisions relies upon research investigating the relationships between neuropsychological and psychosocial status (i.e., ecological validity). Unfortunately, much of this research employs exploratory analyses, an approach that can lead to theoretical ambiguity and ad-hoc interpretations. The current availability and accessibility of analytical tools, like structural equation modeling (SEM), however, permits the testing of specific hypotheses regarding ecological validity and promotes a-priori theory development. In the current study, a theory-driven model of the ecological validity of a neurocognitive assessment was tested against data obtained from individuals with acquired brain injury using SEM. The results provide confirmatory evidence for the ecological validity of neurocognitive constructs and empirical support for a theory-driven analytical approach to ecological validity research.     

Manipulating the evocative and abative effects of an establishing operation: influences on challenging behavior during classroom instruction

In this study we examined the evocative and abative effects of an establishing operation on challenging behavior during classroom instruction for a student with severe disabilities including autism. A prior functional analysis indicated that his challenging behavior was maintained by access to preferred snack items. During classroom instructional sessions these snack items were visible but not available to the student. In other words challenging behavior was placed on extinction during instruction. Immediately prior to instructional sessions the student received either access to snack items or did not receive access to snacks. Access versus no access to snacks prior to instruction was systematically controlled using a multi‐element design. Results demonstrated higher levels of challenging behavior during instruction when the student did not have access to snacks prior to instruction. Very little challenging behavior occurred during instructional sessions when the student had prior access to snacks. Implications for considering the evocative and abative effects of establishing operations when implementing operant extinction in applied settings are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Behavioral Activation as an Early Intervention for Posttraumatic Stress Disorder and Depression Among Physically Injured Trauma Survivors

This paper describes an adaptation of behavioral activation (BA) for the early intervention of posttraumatic stress disorder (PTSD) and depression among physically injured survivors of traumatic injury, and presents pilot data on a small randomized effectiveness trial (N = 8). The application of BA to PTSD is based on the theory that increases in guided activity may break patterns of avoidance that can maintain PTSD. Compared to treatment as usual (TAU), those who received BA showed improvement in PTSD symptom severity from pre- to posttreatment, and there was a trend for the BA group to score better than the TAU group on physical functioning. Contrary to expectation, this brief adaptation did not have an impact on depression. Implications of these results for the effective early intervention after trauma are discussed.     

Use of the computer and Internet among Italian families: first national study.

Although home Internet access has continued to increase, little is known about actual usage patterns in homes. This nationally representative study of over 4,700 Italian households with children measured computer and Internet use of each family member across 3 months. Data on actual computer and Internet usage were collected by Nielsen//NetRatings service and provide national baseline information on several variables for several age groups separately, including children, adolescents, and adult men and women. National averages are shown for the average amount of time spent using computers and on the Web, the percentage of each age group online, and the types of Web sites viewed. Overall, about one-third of children ages 2 to 11, three-fourths of adolescents and adult women, and over four-fifths of adult men access the Internet each month. Children spend an average of 22 hours/month on the computer, with a jump to 87 hours/month for adolescents. Adult women spend less time (about 60 hours/month), and adult men spend more (over 100). The types of Web sites visited are reported, including the top five for each age group. In general, search engines and Web portals are the top sites visited, regardless of age group. These data provide a baseline for comparisons across time and cultures.     

‘Truths that Set Us Free?’: The Use of Rhetoric in Mind-Body-Spirit Books

This article provides a critical qualitative analysis of popular mind-body-spirit books. Typically, these books present a hybrid combining spirituality with self-help and popular psychology. They promise to soothe, heal, and liberate the reader from what is construed as a mundane, desolate life and an environmental and social context of despair. Constructions of transformation and liberation are pervasive in these books. The analysis attends to meaning and rhetoric. Three discourses are delineated, each of which constructs transformation and liberation. In addition, while it is assumed that the authors produce a particular version of spirituality in these books rather than present the truth in a value-neutral way, this analysis attends to the rhetorical strategies that can work to make the authors’ message appear as literal and factual to the reader.