A Common Situation Conducive to Bizarre Distribution Shapes

Conditions conducive to bizarre-shaped distributions are fairly common in certain areas of research where, for perfectly valid reasons, an important causal variable is left uncontrolled. Theoretical rationale and actual examples are given to show how such distributions are generated, to exemplify their shapes, and to indicate their prevalence in practice. An L-shaped type tends to occur when time scores are recorded for a task subject to infrequent but time-consuming errors; other types occur when measuring behavior influenced by social conformity, or under other circumstances. The L shape appears to be far more conducive to nonrobustness than are previously investigated shapes.     

A developmental, biopsychosocial model for the treatment of children with gender identity disorder

This article provides a summary of the therapeutic model and approach used in the Gender Identity Service at the Centre for Addiction and Mental Health in Toronto. The authors describe their assessment protocol, describe their current multifactorial case formulation model, including a strong emphasis on developmental factors, and provide clinical examples of how the model is used in the treatment.     

Testing for empty sets when misclassifications may be present

A test for empty sets is described. This new test is suitable for testing for mutual exclusivity, sets being nested, and many other configurations. It might be hypothesized that two medical conditions do not both occur in individuals. This can be expressed as an empty intersection of the two sets of people with each condition. An important feature of the test is the incorporation of misclassification rates into the analysis. The test utilizes the potential misclassifications for false designations in the sets that are hypothesized to be empty. The test is quite powerful. When the null hypothesis is rejected, follow-up tests on one or more sets that are included in the null hypothesis can be performed using the same new test. MatLab code is supplied.     

Salt tolerance of common green roof and green wall plants

Detrimental effects of road deicing salt on vegetation are well known and have been well studied, with the exception of typical green roof plants, which could experience damage on green roofs with public access and green walls near roadways in cold climates. Two studies were conducted comparing salt tolerance of five Sedum species, two Allium species and a mixture of turf grasses when exposed to six levels of salinity applied either as foliar spray or as liquid applications to the soil. A third study compared salt tolerance when plants were placed at three distances from a major highway. Response variables measured included survival, a health score from 0 to 5, and a growth index. Allium cernuum, A. senscens and S. ellecombianum were relatively tolerant of both saline spray and soil inundation at high saline concentrations in terms of survival, mean health scores, percentage of healthy plants and growth index. Sedum reflexum was much less tolerant of saline spray at higher salinity concentrations and soil inundation regardless of salinity levels. Distance from the road had no effect on plant survival rates but plants farthest from the road had higher mean health scores and a greater percentage of healthy plants than plants closer to the highway.     

“How Could I Have Done This?” Thoughts of Mothers of Children with Fetal Alcohol Syndrome

Biological mothers of children with fetal alcohol syndrome (FAS) must cope with the struggles of parenting a child with special needs with the knowledge that their children’s problems are due to their alcohol use during pregnancy. Qualitative interviews were conducted by telephone with 11 biological mothers of children with FAS. This group of mothers understood their use of alcohol during pregnancy through reliance on the disease model, inaccurate or incomplete knowledge of the consequences of drinking during pregnancy, the advice of others, and a lack of awareness of the pregnancy.     

Comments on “bootstrapping time series models”

We take issue with the main suggestion in Li and Maddala (LiMa) that bootstrapping residuals is always the preferred approach and question some of their guidelines. We show that it can be potentially misleading to mimic the autocovariance structure of residuals, since it can be very different from that of true errors. We emphasize that the residuals are sensitive to model misspecification and generally not a part of the information set. We make constructive suggestions and propose a semiparametric method.     

Minimum-wage increases and employment in franchised fast-food restaurants

Card and Krueger’s (1994) result that employment is unaffected by an increase in the minimum wage in the franchised fast-food restaurant industry appears to be inconsistent with conventional economic analysis. I take a closer look at the franchised fast-food industry and argue that the presence of brand-name capital does not allow franchisees to substitute away from labor or decrease the level of services provided to customers — employment levels in franchised fast-food restaurants are closely tied to sales.