Martin T. Wells

Larger Board Size and Decreasing Firm Value in Small Firms

Abstract Several studies hypothesize a relation between board size and financial performance. Empirical tests of the relation exist in only a few studies of large U.S. firms. We find a significant negative correlation between board size and profitability in a sample of small and midsize Finnish firms. Finding a board-size effect for a new and different class of firms affects the range of explanations for the board-size effect.

Model Selection and Semiparametric Inference for Bivariate Failure-Time Data

Abstract We propose model selection procedures for bivariate survival models for censored data generated by the Archimedean copula family. In route to constructing the selection methodology, we develop estimates of some time-dependent association measures, including estimates of the local and global Kendalls tau, local odds ratio, and other measures defined throughout the literature. We propose a goodness-of-fit-based model selection methodology as well as a graphical approach. We show that the proposed methods have desirable asymptotic properties and perform well in finite samples.

Identifying important predictors for anastomotic leak after colon and rectal resection: prospective study on 616 patients.

Objective:The purpose of this study was to identify patient, clinical, and surgical factors that may predispose patients to anastomotic leak (AL) after large bowel surgery. Background:Anastomotic leak is still one of the most devastating complications following colorectal surgery. Knowledge about factors predisposing patients to AL is vital to its early detection, decision making for surgical time, managing preoperative risk factors, and postoperative complications. Methods:This was a prospective observational, quality improvement study in a cohort of 616 patients undergoing colorectal resection in a single institution with the main outcome being AL within 30 days postoperatively. Some of the predictor variables were age, sex, Charlson Comorbidity Index (CCI), radiation and chemotherapy, immunomodulator medications, albumin, preoperative diagnoses, surgical procedure(s), surgical technique (laparoscopic vs open), anastomotic technique (staple vs handsewn), number of major arteries ligated at surgery, surgeons experience, presence of infectious condition at surgery, intraoperative adverse events, and functional status using 36-Item Short Form General Health Survey. Results:Of the 616 patients, 53.4% were female. The median age of the patients was 63 years and the mean body mass index was 25.9 kg/m2. Of them, 80.3% patients had laparoscopic surgery and 19.5% had open surgery. AL occurred in 5.7% (35) patients. In multivariate analysis, significant independent predictors for leak were anastomoses less than 10 cm from the anal verge, CCI of 3 or more, high inferior mesenteric artery ligation (above left colic artery), intraoperative complications, and being of the male sex. Conclusions:Multiple risk factors exist that predispose patients to ALs. These risk factors should be considered before and during the surgical care of colorectal patients.

A Randomized Controlled Trial of Positive-Affect Intervention and Medication Adherence in Hypertensive African Americans

BACKGROUND Poor adherence explains poor blood pressure (BP) control; however African Americans suffer worse hypertension-related outcomes. METHODS This randomized controlled trial evaluated whether a patient education intervention enhanced with positive-affect induction and self-affirmation (PA) was more effective than patient education (PE) alone in improving medication adherence and BP reduction among 256 hypertensive African Americans followed up in 2 primary care practices. Patients in both groups received a culturally tailored hypertension self-management workbook, a behavioral contract, and bimonthly telephone calls designed to help them overcome barriers to medication adherence. Also, patients in the PA group received small gifts and bimonthly telephone calls to help them incorporate positive thoughts into their daily routine and foster self-affirmation. The main outcome measures were medication adherence (assessed with electronic pill monitors) and within-patient change in BP from baseline to 12 months. RESULTS The baseline characteristics were similar in both groups: the mean BP was 137/82 mm Hg; 36% of the patients had diabetes; 11% had stroke; and 3% had chronic kidney disease. Based on the intention-to-treat principle, medication adherence at 12 months was higher in the PA group than in the PE group (42% vs 36%, respectively; P =.049). The within-group reduction in systolic BP (2.14 mm Hg vs 2.18 mm Hg; P = .98) and diastolic BP (-1.59 mm Hg vs -0.78 mm Hg; P = .45) for the PA group and PE group, respectively, was not significant. CONCLUSIONS A PE intervention enhanced with PA led to significantly higher medication adherence compared with PE alone in hypertensive African Americans. Future studies should assess the cost-effectiveness of integrating such interventions into primary care. Trial Registration clinicaltrials.gov Identifier: NCT00227175.

Assessment and risk analysis of casing and cement impairment in oil and gas wells in Pennsylvania, 2000-2012.

Significance Previous research has demonstrated that proximity to unconventional gas development is associated with elevated concentrations of methane in groundwater aquifers in Pennsylvania. To date, the mechanism of this migration is poorly understood. Our study, which looks at more than 41,000 conventional and unconventional oil and gas wells, helps to explain one possible mechanism of methane migration: compromised structural integrity of casing and cement in oil and gas wells. Additionally, methane, being the primary constituent of natural gas, is a strong greenhouse gas. The identification of mechanisms through which methane may migrate to the atmosphere as fugitive emissions is important to understand the climate dimensions of oil and gas development. Casing and cement impairment in oil and gas wells can lead to methane migration into the atmosphere and/or into underground sources of drinking water. An analysis of 75,505 compliance reports for 41,381 conventional and unconventional oil and gas wells in Pennsylvania drilled from January 1, 2000–December 31, 2012, was performed with the objective of determining complete and accurate statistics of casing and cement impairment. Statewide data show a sixfold higher incidence of cement and/or casing issues for shale gas wells relative to conventional wells. The Cox proportional hazards model was used to estimate risk of impairment based on existing data. The model identified both temporal and geographic differences in risk. For post-2009 drilled wells, risk of a cement/casing impairment is 1.57-fold [95% confidence interval (CI) (1.45, 1.67); P < 0.0001] higher in an unconventional gas well relative to a conventional well drilled within the same time period. Temporal differences between well types were also observed and may reflect more thorough inspections and greater emphasis on finding well leaks, more detailed note taking in the available inspection reports, or real changes in rates of structural integrity loss due to rushed development or other unknown factors. Unconventional gas wells in northeastern (NE) Pennsylvania are at a 2.7-fold higher risk relative to the conventional wells in the same area. The predicted cumulative risk for all wells (unconventional and conventional) in the NE region is 8.5-fold [95% CI (7.16, 10.18); P < 0.0001] greater than that of wells drilled in the rest of the state.

A Randomized Controlled Trial of Positive-Affect Induction to Promote Physical Activity After Percutaneous Coronary Intervention

BACKGROUND Within 1 year after percutaneous coronary intervention, more than 20% of patients experience new adverse events. Physical activity confers a 25% reduction in mortality; however, physical activity is widely underused. Thus, there is a need for more powerful behavioral interventions to promote physical activity. Our objective was to motivate patients to achieve an increase in expenditure of 336 kcal/wk or more at 12 months as assessed by the Paffenbarger Physical Activity and Exercise Index. METHODS Two hundred forty-two patients were recruited immediately after percutaneous coronary intervention between October 2004 and October 2006. Patients were randomized to 1 of 2 groups. The patient education (PE) control group (n = 118) (1) received an educational workbook, (2) received a pedometer, and (3) set a behavioral contract for a physical activity goal. The positive-affect/self-affirmation (PA) intervention group (n = 124) received the 3 PE control components plus (1) a PA workbook chapter, (2) bimonthly induction of PA by telephone, and (3) small mailed gifts. All patients were contacted with standardized bimonthly telephone follow-up for 12 months. RESULTS Attrition was 4.5%, and 2.1% of patients died. Significantly more patients in the PA intervention group increased expenditure by 336 kcal/wk or more at 12 months, our main outcome, compared with the PE control group (54.9% vs 37.4%, P = .007). The PA intervention patients were 1.7 times more likely to reach the goal of a 336-kcal/wk or more increase by 12 months, controlling for demographic and psychosocial measures. In multivariate analysis, the PA intervention patients had nearly double the improvement in kilocalories per week at 12 months compared with the PE control patients (602 vs 328, P = .03). CONCLUSION Patients who receive PA intervention after percutaneous coronary intervention are able to achieve a sustained and clinically significant increase in physical activity by 12 months. Trial Registration clinicaltrials.gov Identifier: NCT00248846.

The Predictability of Punitive Damages

Using one year of jury trial outcomes from 45 of the nations most populous counties, this article shows a strong and statistically significant correlation between compensatory and punitive damages. These findings are replicated in 25 years of punitive damages awards from Cook County, Illinois, and California. In addition, we find no evidence that punitive damages awards are more likely when individuals sue businesses than when individuals sue individuals. With respect to award frequency, juries rarely award punitive damages and appear to be especially reluctant to do so in the areas of law that have captured the most attention, products liability and medical malpractice. Punitive damages are most frequently awarded in business/contract cases and intentional tort cases. The frequency‐of‐award findings are consistent with all major studies of punitive damages.

Quantile comparison functions in two-sample problems, with application to comparisons of diagnostic markers

Abstract In this article a control percentile test, a chi-squared test, and a Kolmogorov-type test are proposed for comparing two distributions from incomplete survival data. These tests are obtained by examining a vertical shift comparison function at a single point, a finite number of points, and an entire set of points on an interval. The proposed methods also have applications in receiver operating characteristic (ROC) analysis, which has been widely used in such diverse fields as signal detection theory, psychology, epidemiology, and medicine. The results are derived under very general conditions that hold for the well-known random censorship and random truncation models. The performances of the proposed procedures are studied using Monte Carlo simulation. The methods are applied to analyze Mayo Clinic ovarian carcinoma data.

Nocturnal Systemic Hypotension Increases the Risk of Glaucoma Progression

OBJECTIVE The objective of this prospective, longitudinal study of patients with normal-tension glaucoma (NTG) was to determine whether patients with nocturnal hypotension are at greater risk for visual field (VF) loss over 12 months than those without nocturnal hypotension. DESIGN Prospective, longitudinal study. PARTICIPANTS Consecutive patients with NTG with at least 5 prior VF tests were screened for eligibility. METHODS The baseline evaluation assessed demographic and clinical characteristics, covering systemic comorbid conditions, including systemic hypertension. All oral and ophthalmologic medications were recorded. A complete ophthalmological examination was performed at baseline and follow-up. Patients had their blood pressure (BP) monitored every 30 minutes for 48 hours with an ambulatory recording device at baseline and 6 and 12 months. MAIN OUTCOME MEASURES The primary outcome was based on the global rates of VF progression by linear regression of the mean VF threshold sensitivity over time (decibels/year). RESULTS Eighty-five patients with NTG (166 eyes; mean age, 65 years; 67% were women) were included. Of the 85 patients, 29% had progressed in the 5 VFs collected before study enrollment. The nocturnal mean arterial pressure (MAP) was compared with the daytime MAP. Multivariate analysis showed that the total time that sleep MAP was 10 mmHg below the daytime MAP was a significant predictor of subsequent VF progression (P<0.02). CONCLUSIONS Cumulative nocturnal hypotension predicted VF loss in this cohort. Our data suggest that the duration and magnitude of decrease in nocturnal blood pressure below the daytime MAP, especially pressures that are 10 mmHg lower than daytime MAP, predict progression of NTG. Low nocturnal blood pressure, whether occurring spontaneously or as a result of medications, may lead to worsening of VF defects.

Multiple Endoplasmic Reticulum-to-Nucleus Signaling Pathways Coordinate Phospholipid Metabolism with Gene Expression by Distinct Mechanisms

In many organisms the coordinated synthesis of membrane lipids is controlled by feedback systems that regulate the transcription of target genes. However, a complete description of the transcriptional changes that accompany the remodeling of membrane phospholipids has not been reported. To identify metabolic signaling networks that coordinate phospholipid metabolism with gene expression, we profiled the sequential and temporal changes in genome-wide expression that accompany alterations in phospholipid metabolism induced by inositol supplementation in yeast. This analysis identified six distinct expression responses, which included phospholipid biosynthetic genes regulated by Opi1p, endoplasmic reticulum (ER) luminal protein folding chaperone and oxidoreductase genes regulated by the unfolded protein response pathway, lipid-remodeling genes regulated by Mga2p, as well as genes involved in ribosome biogenesis, cytosolic stress response, and purine and amino acid metabolism. We also report that the unfolded protein response pathway is rapidly inactivated by inositol supplementation and demonstrate that the response of the unfolded protein response pathway to inositol is separable from the response mediated by Opi1p. These data indicate that altering phospholipid metabolism produces signals that are relayed through numerous distinct ER-to-nucleus signaling pathways and, thereby, produce an integrated transcriptional response. We propose that these signals are generated in the ER by increased flux through the pathway of phosphatidylinositol synthesis.