Dynamic Models for Dynamic Theories: The Ins and Outs of Lagged Dependent Variables

Nathan J. Kelly Department of Political Science, University of Tennessee, 1001 McClung Tower, Knoxville, TN 37996-0410 e-mail: luke.keele{at}mail.polisci.ohio-state.edu (corresponding author) e-mail: nathan.j.kelly{at}gmail.com A lagged dependent variable in an OLS regression is often usedas a means of capturing dynamic effects in political processesand as a method for ridding the model of autocorrelation. Butrecent work contends that the lagged dependent variable specificationis too problematic for use in most situations. More specifically,if residual autocorrelation is present, the lagged dependentvariable causes the coefficients for explanatory variables tobe biased downward. We use a Monte Carlo analysis to assessempirically how much bias is present when a lagged dependentvariable is used under a wide variety of circumstances. In ouranalysis, we compare the performance of the lagged dependentvariable model to several other time series models. We showthat while the lagged dependent variable is inappropriate insome circumstances, it remains an appropriate model for thedynamic theories often tested by applied analysts. From theanalysis, we develop several practical suggestions on when andhow to use lagged dependent variables on the right-hand sideof a model.     

Creating a home to promote recovery: the physical environments of Oxford House

The interior and exterior physical characteristics of substance abuse recovery program dwellings (11 woman, 44 men) from three geographic sections of the United States were assessed at creating a "house-as-home" for residents. Although each house was independently governed and operated by residents, results indicated vast similarities among the interior characteristics, amenities, and structural aspects. These rented dwellings also had similar well-maintained exterior characteristics, despite their geographic locations. Follow-up interviews of former residents indicated that these house characteristics and amenities helped create a sense of home not found in traditional institutional facilities. Results suggested that residents of self-governed independently operated recovery houses may create and maintain safe and sober settings that elicit a sense of home among residents.     

Sudden unexpected death in epilepsy: a retrospective study

Patients with epilepsy have a mortality rate higher than that of the general population; sudden unexpected death represents a significant category of mortality in these patients. The precise frequency of occurrence of sudden unexpected death in epilepsy (SUDEP) is not well defined, with a range of 1 in 370 to 1100 in the general epileptic population. A major difficulty with incidence studies is the continued reluctance in using the term SUDEP as a cause of death, making reliance solely on death certificates inconsistent and incomplete. Knowledge about SUDEP remains limited, as no single common risk factor has yet been identified, although predisposing conditions have been suggested. The purpose of this study is to review the association between several clinical variables and SUDEP to elucidate risk factors. The characteristics of the 67 cases in this series correlate with published findings in previous studies. Attributes that may be used to define an at-risk group of epileptics include age less than 40 years, male gender, long history of seizure disorder, undermedication or poorly controlled seizure activity, and mental or physical stress. Education of physicians as to the existence of SUDEP and risk factors is imperative in improving patient education and reduction in mortality.     

Life Constraints and Psychological Well-Being of Domestic Violence Shelter Graduates

Psychosocial adjustment and life constraints of 81 domestic violence shelter graduates were examined via field interviews in the community, assessing womens current life status, satisfaction with core life domains, and violence experience, pre- and post-shelter. Psychometric scales for depression and trauma symptoms were also administered. Participants had received extensive services in either an emergency or a transitional living shelter. Although fairly satisfied across life domains, many had serious post-shelter financial hardships. Most importantly, they reported remarkably little post-shelter violence exposure, either within or outside of romantic relationships. Despite now living independently, 43% and 75% reported clinical levels of depression and trauma symptoms, respectively. In hierarchical stepwise regressions, depression was related to womens childhood sexual abuse, dissatisfaction with housing and their own parenting, and experience of financial difficulties conjoined with public assistance. Trauma symptoms were associated with childhood sexual abuse and post-shelter financial difficulties. The impaired psychosocial functioning and life difficulties of these predominantly successful domestic violence survivors highlights the need for specialized shelter intervention and continuity of care in the community.     

Psychological Distress of Children and Mothers in Domestic Violence Emergency Shelters

Abused mothers and their school-aged children who recently entered domestic violence emergency shelters were assessed by individual interview and psychometric measures. Children had positiveviews of the shelter residence. Mothers and children reported high-quality relationships with eachother. Children came from highly violent homes, and the majority had attempted to intervene in theinteradult violence. Hierarchical multiple regressions were conducted on child PTSD symptoms, child behavior problems, and maternal depression, anxiety, and anger. Child PTSD symptoms were associated with amount of physical violence. Child behavioral problems were related to mother anxiety andanger. The predictors of maternal emotional distress varied. Depression was associated with sexualabuse, child physical intervention, and quality of mother–child relationship; anxiety was related to witnessing child abuse, child age, and child internalizing behaviors; anger was associated with abuse-related injuries, violence frequency, and child internalizing behaviors. Augmentationof shelter-based interventions for children's trauma, maternal emotional distress, and parenting are discussed.     

Gender Crimes Jurisprudence in the ICTR: Positive Developments

Considering the magnitude of rape and other sexual crimes perpetratedduring the Rwandan genocide, gender crimes prosecutions at theInternational Criminal Tribunal for Rwanda (ICTR) have beeninadequate so far. Nonetheless, the ICTR case law must be commendedfor the impulse given, with and after Akayesu, to the criminalizationand punishment of gender-related violence. This paper pointsto the achievements of the ICTR case law in this respect.     

Fatal bupivacaine intoxication following unusual erotic practices

A fatal drug overdose is described which involved unusual erotic practices. A 54-year-old male was discovered supine on the floor surrounded by sexual paraphernalia, syringes, and medications including three empty bottles of bupivacaine. Acute and chronic injection sites of the external genitalia with contusions, scarring, focal necrosis, and calcification were present at autopsy. Toxicology revealed femoral blood, heart blood, and vitreous bupivacaine concentrations of 3.8, 2.8 and 1.3 mg/L, respectively. The urine bupivacaine concentration was 11.4 mg/L. The cause of death was attributed to bupivacaine intoxication and the manner of death was accidental.     

Using STR analysis to detect human DNA from exploded pipe bomb devices

This study investigated the possibility of recovering a bomb assembler's DNA from an exploded pipe bomb device. Metal and polyvinyl chloride (PVC) pipes were examined to determine if one surface type would allow better DNA recovery than the other. Ten subjects each handled components of one metal and one PVC pipe bomb. The bombs were exploded, the fragments were collected and swabbed using the double swab technique, and the samples were extracted, quantified, amplified, and genotyped using polymerase chain reaction/short tandem repeat (PCR/STR). Of the 20 bombs handled by the subjects, four bombs gave reportable results that matched the subject's known DNA profiles. An additional eight profiles, also matching the subject's known DNA profiles, were generated but were below the reportable threshold. There was no difference in the success rate of obtaining DNA profiles related to the use of either PVC or metal in the manufacture of the pipe bomb. The variables that appeared to have the greatest influence on the success of generating a DNA profile were the amount of fragmentation and subsequent recovery of the bomb fragments. It is suspected that successful DNA profiling could also be dependent upon the bomb assembler's propensity to slough skin cells on objects they handled.     

Organizational downsizing and age discrimination litigation: the influence of personnel practices and statistical evidence on litigation outcomes

The present study examined relationships between reduction-in-force (RIF) personnel practices, presentation of statistical evidence, and litigation outcomes. Policy capturing methods were utilized to analyze the components of 115 federal district court opinions involving age discrimination disparate treatment allegations and organizational downsizing. Univariate analyses revealed meaningful links between RIF personnel practices, use of statistical evidence, and judicial verdict. The defendant organization was awarded summary judgment in 73% of the claims included in the study. Judicial decisions in favor of the defendant organization were found to be significantly related to such variables as formal performance appraisal systems, termination decision review within the organization, methods of employee assessment and selection for termination, and the presence of a concrete layoff policy. The use of statistical evidence in ADEA disparate treatment litigation was investigated and found to be a potentially persuasive type of indirect evidence. Legal, personnel, and evidentiary ramifications are reviewed, and a framework of downsizing mechanics emphasizing legal defensibility is presented.