The mad estimator: when is it non-linear? applications to two-way design models

The mean absolute deviation (MAD) estimator has recently received a great deal of attention as applied to full-rank linear regression models. This paper provides a necessary and sufficient condition for the MAD estimator to be a non-linear estimator, in which case conditions for the variance of the MAD estimator to be larger or smaller than those for OLS are, in general, unknown. The non-linearity of the MAD estimator is examined for several two-way designs; in particular (1) randomized block design (2) two-way nested design (3) two-way classification with interaction and (4) partially balanced incomplete block design     

Entwickeln im Team – Effekte für den Einzelnen

This study tested the effects of a 2-day team building intervention on team members’ team identification, social support and collective self-efficacy. Members (n?=?32) of three teams from different sectors completed questionnaires before, directly after and six weeks after the team building intervention. Two teams served as control groups. Results showed lasting positive effects of team building on identification, support and collective self-efficacy in the training groups but no changes in the control groups.     

A Preliminary Investigation of a Telephone Administration of the Quality of Marriage Index

Follow‐up data collection presents many challenges for longitudinal research. Validating paper‐and‐pencil assessments for use via telephone may alleviate these issues. This study evaluates psychometric properties of the Quality of Marriage Index (QMI; Norton, 1983, Journal of Marriage and the Family, 45, 141) when administered by telephone and compares scores with the paper‐and‐pencil version. Participants included women with major depressive disorder and dyadic discord and their male spouses (n = 24 couples). Results suggest excellent scale reliability for the verbal QMI. However, a significant mean difference was found: participants scored on average 3 points higher on the telephone‐administered QMI than on the written QMI. Recommendations for future research and clinical implications are discussed.     

College Student Behavior: A Ten-Year Look

Abstract

Lester and Perez¹ have suggested that student behavior can be usefully construed in terms of a traditional-hedonic, implicit value system. They demonstrated that drug use and sexual activity provide simple behavioral anchors for this dimension, and observed an increasingly hedonic orientation among students. Ten years after their initial study, the student population at the same institution was again sampled using an anonymous questionnaire. The 1980 sample included 208 subjects, and these were compared with 688 subjects who responded to the 1970 survey. This comparison was supplemented by an intensive week-long study of 53 students within one campus living unit.

Significant increases in pre-college sexual activity were noted for both men and women. Marijuana use in high school also increased for both men and women during this period, while alcohol use increased only among women. Previously observed differences between male and female pre-college sexual activity and marijuana use had largely disappeared by 1980. Significant increases in sexual activity while in college were found for women but not for men. For men, overall marijuana and alcohol use in college did not change during the study period, but there was an increase in the frequent use of these drugs. Increases in all categories of marijuana use were noted among women, along with overall increases in their alcohol use. The significant differences between male and female marijuana use noted in the 1970 study were absent in 1980. The intensive week-long study revealed that alcohol use was part of the daily lives of one-third to two-thirds of the students sampled, although they reported interpersonal conflicts, absences from class, accidents, and injuries among the consequences of their drinking. A significant inverse relationship between sleep and alcohol use was observed among women, but not among men.

These data suggest that student behavior has become increasingly hedonic during the past ten years, with women in particular closing the gap which previously differentiated their behavior from that of their male peers. Institutions of higher learning must take these changes into account in the planning of academic programs, residential life, and health services.     

Differences in Caregiver Self-Efficacy and Satisfaction Related to Sexual Abuse of Offspring

Research suggests parents of sexually abused children may experience negative perceptions of themselves and their parenting abilities following the victimization of their children, which may influence the recovery process in treatment for these families. This study assessed perceived self-efficacy and parenting satisfaction among female caregivers of sexually abused children and female caregivers whose children were not victimized. Results indicated that caregivers of child victims had significantly lower levels of perceived parenting efficacy than their counterparts. There were no significant differences found between groups with regard to parenting satisfaction. The results highlight the importance of evaluating perceived parenting competence in the treatment of nonoffending caregivers in order to facilitate optimal treatment of the child victim and all members of the family system.     

The United States Economic Crisis: Young Adults’ Reports of Economic Pressures, Financial and Religious Coping and Psychological Well-Being

Using a sample of 222 young adults attending college, the present study examined the relative contribution of young adults’ perceived economic pressures, financial coping and religious meaning-making coping strategies in accounting for variation in their reports of psychological well-being within the context of the United States economic crisis. Results suggest a direct relationship between perceived economic pressure and psychological well-being such that young adults who reported having to make more economic adjustments as a result of economic crisis also reported higher levels of depressed mood and anxiety. Young men and women who reported having to make fewer economic adjustments and being able to meet their material needs reported higher levels of life satisfaction. Regardless of young adults’ self-reported level of economic pressures, the use of education and communication financial coping strategies was related to lower levels of self-reported anxiety and depressed mood and greater life satisfaction. Viewing the financial crisis as a punishment from God was generally associated with young adults’ reports of greater depressed mood and less life satisfaction. Implication of findings for research and practice are discussed.     

The value of rescheduling functionality within standard MRP packages

One of the basic functions of an MRP system is to issue rescheduling messages that urge the planner tospeed up or slow down open orders. It seems in practice that these messages are not used at all by planners. This is mostly due to the inaccuracy of MRP, that more or less ignores safety time, safety stocks and lotsize flexibility in the calculation of reschedule-in messages. Reschedule-out messages are usually ignored because planners do not see the value of the message. Other reasons for not adhering to rescheduling messages are a lack of maintenance of MRP parameters or simply the wrong use of the MRP function. In the future, MRP rescheduling functionality will be used even less than today, due to the changing role of MRP within the planning framework. With the uprise of finite capacity scheduling packages, MRP is being pushed one level upward in the planning hierarchy. This means that rescheduling functionalities for the short term will become completely obsolete in MRP systems.     

Model diagnostics for marginal regression analysis of correlated binary data

We propose several diagnostic methods for checking the adequacy of marginal regression models for analyzing correlated binary data. We use a parametric marginal model based on latent variables and derive the projection (hat) matrix, Cook's distance, various residuals and Mahalanobis distance between the observed binary responses and the estimated probabilities for a cluster. Emphasized are several graphical methods including the simulated Q-Q plot, the half-normal probability plot with a simulated envelope, and the partial residual plot. The methods are illustrated with a real life example.     

Posture Development in Infants at Heightened versus Low Risk for Autism Spectrum Disorders

Evidence suggests that children and adults diagnosed with autism spectrum disorders (ASD) exhibit difficulties with postural control. Retrospective video studies of infants later diagnosed with ASD indicate that infants who eventually receive an ASD diagnosis exhibit delays in postural development. This study investigates early posture development prospectively and longitudinally in 22 infants at heightened biological risk for ASD (HR) and 18 infants with no such risk (Low Risk; LR). Four HR infants received an autism diagnosis (AD infants) at 36 months. Infants were videotaped at home at 6, 9, 12, and 14 months during everyday activities and play. All infant postures were coded and classified as to whether or not they were infant‐initiated. Relative to LR infants, HR infants were slower to develop skill in sitting and standing postures. AD infants exhibited substantial delays in the emergence of more advanced postures and initiated fewer posture changes. Because posture advances create opportunities for infants to interact with objects and people in new and progressively more sophisticated ways, postural delays may have cascading effects on opportunities for infant exploration and learning. These effects may be greater for infants with ASD, for whom posture delays are more significant.