Variance In Improvement Research Articles

Bayesian Estimation and Optimization for Learning Sequential Regularized Portfolios

This paper incorporates Bayesian estimation and optimization into portfolio selection framework, particularly for high-dimensional portfolio in which the number of assets is larger than the number of observations. We leverage a constrained 𝓁1 minimization approach, called linear programming optimal (LPO) portfolio, to directly estimate effective parameters appearing in the optimal portfolio. We propose two refinements for the LPO strategy. First, we explore improved Bayesian estimates, instead of sample estimates, of the covariance matrix of asset returns. Second, we introduce Bayesian optimization (BO) to replace traditional grid-search cross-validation (CV) in tuning hyperparameters of the LPO strategy. We further propose modifications in the BO algorithm by (1) taking into account time-dependent nature of financial problems and (2) extending commonly used expected improvement (EI) acquisition function to include a tunable trade-off with the improvement's variance (EIVar). Allowing a general case of noisy observations, we theoretically derive the sub-linear convergence rate of BO under the newly proposed EIVar and thus our algorithm has no regret. Our empirical studies confirm that the adjusted BO result in portfolios with higher out-of-sample Sharpe ratio, certainty equivalent, and lower turnover compared to those tuned with CV. This superior performance is achieved with significant reduction in time elapsed, thus also addressing time-consuming issues of CV. Furthermore, LPO with Bayesian estimates outperform original proposal of LPO, as well as the benchmark equally weighted and plug-in strategies.

Phased-array combination of 2D MRS for lipid composition quantification in patients with breast cancer

Lipid composition in breast cancer, a central marker of disease progression, can be non-invasively quantified using 2D MRS method of double quantum filtered correlation spectroscopy (DQF-COSY). The low signal to noise ratio (SNR), arising from signal retention of only 25% and depleted lipids within tumour, demands improvement approaches beyond signal averaging for clinically viable applications. We therefore adapted and examined combination algorithms, designed for 1D MRS, for 2D MRS with both internal and external references. Lipid composition spectra were acquired from 17 breast tumour specimens, 15 healthy female volunteers and 25 patients with breast cancer on a clinical 3 T MRI scanner. Whitened singular value decomposition (WSVD) with internal reference yielded maximal SNR with an improvement of 53.3% (40.3–106.9%) in specimens, 84.4 ± 40.6% in volunteers, 96.9 ± 54.2% in peritumoural adipose tissue and 52.4% (25.1–108.0%) in tumours in vivo. Non-uniformity, as variance of improvement across peaks, was low at 21.1% (13.7–28.1%) in specimens, 5.5% (4.2–7.2%) in volunteers, 6.1% (5.0–9.0%) in peritumoural tissue, and 20.7% (17.4–31.7%) in tumours in vivo. The bias (slope) in improvement ranged from − 1.08 to 0.21%/ppm along the diagonal directions. WSVD is therefore the optimal algorithm for lipid composition spectra with highest SNR uniformly across peaks, reducing acquisition time by up to 70% in patients, enabling clinical applications.

Testing a theory of strategic implementation leadership, implementation climate, and clinicians\u2019 use of evidence-based practice: a 5-year panel analysis

BackgroundImplementation theory suggests that first-level leaders, sometimes referred to as middle managers, can increase clinicians’ use of evidence-based practice (EBP) in healthcare settings by enacting specific leadership behaviors (i.e., proactive, knowledgeable, supportive, perseverant with regard to implementation) that develop an EBP implementation climate within the organization; however, longitudinal and quasi-experimental studies are needed to test this hypothesis.MethodsUsing data collected at three waves over a 5-year period from a panel of 30 outpatient children’s mental health clinics employing 496 clinicians, we conducted a quasi-experimental difference-in-differences study to test whether within-organization change in implementation leadership predicted within-organization change in EBP implementation climate, and whether change in EBP implementation climate predicted within-organization change in clinicians’ use of EBP. At each wave, clinicians reported on their first-level leaders’ implementation leadership, their organization’s EBP implementation climate, and their use of both EBP and non-EBP psychotherapy techniques for childhood psychiatric disorders. Hypotheses were tested using econometric two-way fixed effects regression models at the organization level which controlled for all stable organizational characteristics, population trends in the outcomes over time, and time-varying covariates.ResultsOrganizations that improved from low to high levels of implementation leadership experienced significantly greater increases in their level of EBP implementation climate (d = .92, p = .017) and within-organization increases in implementation leadership accounted for 11% of the variance in improvement in EBP implementation climate beyond all other covariates. In turn, organizations that improved from low to high levels of EBP implementation climate experienced significantly greater increases in their clinicians’ average EBP use (d = .55, p = .007) and within-organization improvement in EBP implementation climate accounted for 14% of the variance in increased clinician EBP use. Mediation analyses indicated that improvement in implementation leadership had a significant indirect effect on clinicians’ EBP use via improvement in EBP implementation climate (d = .26, 95% CI [.02 to .59]).ConclusionsWhen first-level leaders increase their frequency of implementation leadership behaviors, organizational EBP implementation climate improves, which in turn contributes to increased EBP use by clinicians. Trials are needed to test strategies that target this implementation leadership–EBP implementation climate mechanism.

The Influence of Problem Specific Neighborhood Structures in Metaheuristics Performance

Metaheuristics (MH) aptitude to move past local optimums makes them an attractive technique to approach complex computational problems, such as the Travelling Salesman Problem (TSP), but there is lack of information on the parameterization procedure and the appropriate parameters to improve MHs’ performance. In this paper the parameterization procedure of Simulated Annealing (SA) and Discrete Artificial Bee Colony (DABC) is addressed, with a focus on the Neighborhood Structure (NS). Numerous NS have been proposed for specific problems, which seem to indicate that the NS is a special parameter, whose optimization is independent of other parameters. The performance of eight NS was examined with SA and DABC under two optimization constraints, regarding computational time variation, to determine if there is one appropriate NS for the TSP problem, independent of the rest of the parameters of the optimization procedure. The computational study carried out for comparing the evaluation of the NS, including a statistical analysis, demonstrated a nonproportional increase in the performance of DABC with some NS. For SA the improvement of the solutions appeared to be more uniform with an almost nonexistent variance in improvement.

Effect of floor reaction ankle–foot orthosis on crouch gait in patients with cerebral palsy

Floor reaction ankle-foot orthoses are commonly prescribed to improve knee extension of children with cerebral palsy having crouch gait. Their effectiveness is debated. Therefore, the objective of this study is to optimize current prescription criteria for the improvement of crouch gait. Cross-sectional interventional study. A total of 22 patients with bilateral spastic cerebral palsy, between 6 and 17 years, Gross Motor Function Classification System II-IV participated in this study. Instrumented gait analysis was done under three conditions: barefoot, shoed, and with orthotics. Patients were divided into two groups: good and non-responders with more and less than 8.8° improvement of knee extension during walking, respectively. A multiple predictor analysis was done on parameters that were different between groups. In total, 12 of 22 patients showed good response in knee extension with a mean change of 17° (standard deviation = 5°). Good responders showed a significantly smaller walking velocity, knee extension strength, ankle plantarflexion strength, and greater external foot progression angle compared to non-responders. Foot progression angle together with ankle plantarflexion strength explained 37% of the variance in improvement of knee extension. With appropriate patient selection, an improvement of crouch gait by ankle-foot orthoses of 17° (standard deviation = 5°) can be expected. Patients with slow velocity, weak plantarflexors, and external foot progression benefit most. Joint contractures were no contraindications. Clinical relevance This study showed that gait in patients with low functional level benefit most from ankle-foot orthoses. Unlike in patients with higher functional status, contractures of hip, knee, and ankle did not reduce the positive effects on gait. The suggested prescription criteria may help to better select appropriate patients for orthotics.

Examination of Individual Differences in Outcomes From a Randomized Controlled Clinical Trial Comparing Formal and Informal Individual Auditory Training Programs

The purpose of this study was to determine if patient characteristics or clinical variables could predict who benefits from individual auditory training. A retrospective series of analyses were performed using a data set from a large, multisite, randomized controlled clinical trial that compared the treatment effects of at-home auditory training programs in bilateral hearing aid users. The treatment arms were (a) use of the 20-day computerized Listening and Communication Enhancement program, (b) use of the 10-day digital versatile disc Listening and Communication Enhancement program, (c) use of a placebo "books-on-tape" training, and (d) educational counseling (active control). Multiple linear regression models using data from 263 participants were conducted to determine if patient and clinical variables predicted short-term improvement on word-recognition-in-noise abilities, self-reported hearing handicap, and self-reported hearing problems. Baseline performance significantly predicted performance on each variable, explaining 11%-17% of the variance in improvement. The treatment arm failed to emerge as a significant predictor with other clinical variables explaining less than 9% of the variance. These results suggest that hearing aid users who have poorer aided word-recognition-in-noise scores and greater residual activity limitations and participation restrictions will show the largest improvement in these areas.

Effects of therapeutic relationship, expectancy, and credibility in breathing therapies for anxiety.

The authors investigated the effects of the quality of the therapeutic alliance, expectancy of improvement, and credibility of treatment on the outcome of two breathing therapies for anxiety and panic. Data were collected during a randomized clinical trial evaluating the efficacy of two theoretically opposing, end-tidal pCO2 feedback-assisted breathing therapies for patients experiencing anxiety attacks. In this study, five weekly individual breathing therapy sessions were administered for the patients who were experiencing anxiety attacks as symptoms of various anxiety disorders. The outcome of this trial indicated that regardless of the opposing breathing instructions (raise or lower pCO2) used in the two breathing therapies, patients in both treatment groups improved equally after treatment. Nonspecific factors rather than the different directions of pCO2 changes could have played a role in the improvement. Regression analyses showed that for both therapies patient-rated therapeutic alliance was predictive of improvement at the 1-month follow-up, and that patient-rated confidence that the therapy would produce improvement, an aspect of its credibility, accounted for almost half of the variance in improvement at the 6-month follow-up. Thus, two factors usually considered nonspecific were identified to be potent predictors of treatment outcome.

Effect of Comorbid Depression on Cognitive Behavioural Group Therapy for Social Anxiety Disorder

AbstractMany individuals seeking treatment for social anxiety disorder (SAD) also meet criteria for a comorbid depressive disorder. Little is known, however, about how a comorbid depressive disorder affects social anxiety treatment. This study examined 61 participants with SAD and 72 with SAD and a comorbid depressive disorder (SAD+D) before and after 12 weeks of cognitive behavioural group therapy (CBGT) for social anxiety. Although patients with SAD+D reported more severe symptoms of social anxiety and depression at pretreatment, treatment was similarly effective for individuals with SAD and SAD+D. However, individuals with SAD+D continued to report higher symptom severity at post-treatment. Interestingly, CBGT for social anxiety also led to improvements in depressive symptoms despite the fact that depression was not targeted during treatment. Improvement in social anxiety symptoms predicted 26.8% of the variance in improvement in depressive symptoms. Results suggest that depressive symptoms need not be in remission for individuals to benefit from CBGT for social anxiety. However, more than 12 sessions of CBGT may be beneficial for individuals with comorbid depression.

Efficient cognitive operations predict skill acquisition

The present study examined the relationship between performance on the ALTM task and improvement in Stroop task performance across trials. Prior research indicated that the ALTM task may be capturing individual differences in facilitation of procedural memory but has often been confounded with long-term semantic priming due to the nature of the task. The Stroop task was chosen because related semantic information is largely irrelevant to performance. Path analysis revealed that ALTM task performance accounted for 11.3% of the variance in improvement in color–word Stroop improvement over two sessions. No other hypothesized relationships were significant in the path model. Results are discussed in light of the apparent relationship between ALTM task performance and an individual's ability to acquire new procedural memory traces. Implications of these findings are discussed and future directions for continued research are proposed.

English

AIM: To compare the efficacy of lorazepam and chlordiazepoxide in alcohol withdrawal in an open label design. METHOD: The study sample consisted of 103 consecutive admissions to the de addiction ward, which after informed consent and selection based on inclusion criteria were randomised to two groups. A prospective inpatient analysis of withdrawal was done using CIWA-Ar and a comparison of the efficacy of chlordiazepoxide and lorazepam was done post randomization. Measurements the initial withdrawal assessment and subsequent progress of withdrawal was assessed using CIWA-Ar. The rate of withdrawal and total duration of withdrawal was compared among the two groups. RESULTS: Lorazepam treated group showed a significant difference in the rate of improvement over 48 hours compared to chlordiazepoxide group (71.3% vs. 57.4%; p=0.000). The total duration of withdrawal was also significantly lesser with lorazepam (5.7 vs. 6.9 days; p=0.001). A stepwise linear regression showed that 63% of the variance in improvement was related to the drug, thus proving the superiority of lorazepam. CONCLUSION: Lorazepam is more effective than chlordiazepoxide in alcohol withdrawal in both faster rate of fall of withdrawal severity and bringing down the total duration of withdrawal

Weight Loss and Improved Gross Motor Coordination in Children as a Result of Multidisciplinary Residential Obesity Treatment

This study evaluated the short-term effectiveness of a multidisciplinary residential obesity treatment program by describing changes in body weight, related measures, and gross motor co-ordination. Secondarily, it was examined to what extent the amount of relative weight loss achieved by overweight and obese (OW/OB) participants explained the projected improvement in gross motor co-ordination. Thirty-six OW/OB children (aged 10.5 ± 1.4 years, 12 girls and 24 boys) were recruited at the Zeepreventorium VZW (De Haan, Belgium), where they followed a specific program consisting of moderate dietary restriction, psychological support, and physical activity. For reference purposes, an additional group of 36 age- and gender-matched healthy-weight (HW) children was included in the study. Anthropometric measures were recorded and gross motor co-ordination was assessed using the Körperkoordinationstest für Kinder (KTK) on two occasions with an interval of 4 months. Regardless of the test moment, OW/OB participants displayed significantly poorer KTK performances (P < 0.001). However, treatment was found to be efficacious in decreasing body weight (Δ 17.9 ± 3.1%, P < 0.001) and generating a significant progress in gross motor co-ordination performance, with a greater increase in KTK score(s) from baseline to re-test as compared to HW peers (P < 0.01). Within the OW/OB group, the amount of relative weight loss explained 26.9% of the variance in improvement in overall KTK performance. Therefore, multidisciplinary residential treatment and concomitant weight loss can be considered an important means to upgrade OW/OB children's level of gross motor co-ordination, which in turn may promote physical activity participation.

The relative contributions of fear and disgust reductions to improvements in spider phobia following exposure-based treatment

The present study examines the relative contributions of changes in state fear and disgust emotions to improvements in spider phobia observed with exposure-based treatment. Sixty-one treatment-seeking spider fearful individuals underwent a one-session exposure in vivo treatment. Growth curve analyses indicated that treatment was associated with significant improvements in state fear and disgust reactions to a live spider and self-reported trait spider phobia symptoms. Mediation analyses demonstrated that changes over time in state fear and disgust each explained unique variance in improvements in phobic symptoms over time. Examination of the effect size of the mediated pathways suggests that changes in fear and changes in disgust are important to reductions in the severity of spider phobia symptoms during exposure-based treatment. The implications of these findings for conceptualizing the role of fear and disgust emotions in the maintenance and treatment of spider phobia are discussed.

Changes in reported physical health symptoms and social function with prolonged exposure therapy for chronic posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is associated with significant health risk, illness, and functional impairment, e.g., Green and Kimerling [2004: Physical Health Consequences of Exposure to Extreme Stress. Washington, DC: American Psychological Association] Kimerling et al. [2000: Trauma and Health: J Trauma Stress 13:115-128]. These analyses examined whether negative health perceptions and general social functioning change with treatment of chronic PTSD among women from a randomized controlled study comparing prolonged exposure (PE; n=48) or PE combined with cognitive restructuring (PE/CR; n=40) to waitlist (n=19; Foa et al., 2005: J Consult Clin Psychol 73:953-964]. Self- reported physical health difficulties were significantly reduced in the PE and PE/CR conditions compared to the waitlist condition. These reductions did not demonstrate significant change during the 12 month follow-up period. Self-reported discomfort associated with physical health difficulties did not demonstrate significant change over treatment. No difference was detected between the active treatment and waitlist conditions. Both the PE and PE/CR groups reported improved social functioning at post treatment compared to the waitlist. Additional improvement in general social functioning was found between 3 and 12 month follow-up assessments. Changes in PTSD and depressive symptoms over treatment accounted for 29% of the variance in reduction of reported health problems and 30% of the variance in improvement of general social functioning. Importantly, only changes in PTSD symptoms significantly contribute to the model predicting change in physical health problems with depression associated only at a trend level. However, collinearity between PTSD and depression makes interpretation difficult. Negative health perceptions and general social function improve with PE. Changes in depression and PTSD with treatment are related to these changes.

Therapeutic Alliance and Treatment Progress in Couple Psychotherapy

This study examined the ability of the therapeutic alliance to predict treatment progress on individual- and relationship-level variables from the early to middle phase of couple treatment. Although alliance did not predict progress in individual functioning, it accounted for 5-22% of the variance in improvement in marital distress. Women's mid-treatment alliance uniquely predicted improvement in marital distress, over and above early treatment alliance. When men's alliances with the therapist were stronger than their partners' at session 8, couples showed more improvement in marital distress. Treatment response was also positively associated with women's ratings of their partners' alliance. Results confirm that the therapeutic alliance in conjoint treatment is composed of distinct client subsystems that are useful predictors of treatment progress.

Discussing multisource feedback with raters and performance improvement

This paper hypothesized that ratees who share their multisource feedback with raters and ask for suggestions would improve more than other ratees. The participants were 5,335 ratees in a large, global corporation who received multisource feedback. Nine months after the initial survey, there was a follow‐up survey in which raters indicated whether the feedback recipient had shared the feedback and asked for suggestions. One year after the initial survey, there was a second multisource feedback survey. It was found that sharing feedback and asking for suggestions accounted for only a very small (albeit statistically significant) proportion of variance in improvement over time. This paper discusses factors that may affect the impact of sharing feedback and asking for suggestions following multisource feedback.

Ceiling and floor effects in sleep research.

Ceiling and floor effects dictate that the efficacy of sleep-promoting stimuli should be proportional to the degree of pre-stimulus sleep impairment. This review addressed CF effects in polysomnographic research involving hypnotic drugs and exercise. Correlations of placebo/baseline levels of sleep with changes in sleep following hypnotic or exercise treatment were assessed across both literatures. CF effects were further addressed by comparing sleep-promoting effects of hypnotics vs exercise, after ANCOVA control for substantial baseline differences reported in studies of these stimuli. Significant correlations between placebo-baseline levels and sleep changes were observed following both hypnotic and exercise stimuli. Indeed, approximately 60% of the variance in improvement in sleep latency (SOL), wakefulness after sleep onset (WASO) and total sleep time (TST) following hypnotic treatment was associated with differences in baseline levels. ANCOVAs revealed significantly greater decreases in SOL and WASO following hypnotics compared with exercise. However, no significant difference between stimuli was found for TST, and exercise elicited a significantly greater increase in slow wave sleep. Similar results were found when a comparison between hypnotics and exercise was limited to good sleepers. The results show powerful CF influences on sleep responses to hypnotics and exercise and suggest a need for comparing these treatments in poor sleepers.

Predictors of child psychological changes during family-based treatment for obesity.

To explore the influence of 1-year changes in child obesity and maternal psychopathology on changes in child psychological problems. Hierarchical regression models were used to predict child psychological change, with demographic variables, maternal psychological change, and child percentage overweight change as predictors. Pediatric obesity research clinic. Clinic sample of 116 obese 8- to 12-year-old children and their mothers. Family-based behavioral weight-control program. Child psychopathology was assessed via mother-reported Child Behavior Checklists and maternal psychopathology was determined by standardizing scores on the Cornell Medical Index and the Symptoms Checklist-90-Revised. Significant improvements were observed in child percentage overweight (-20.1% overweight), and child and maternal psychopathology. Improved maternal psychopathology accounted for a significant amount of variance in improvements in the Child Behavior Checklist total Problems Scale and internalizing and externalizing problems subscales. Decreased obesity accounted for a significant amount of variance in improvements in the Total Competence scale and, somatic complaints, social problems and social competence subscales of the Child Behavior Checklist. Significant interactions of child obesity change by sex were found for Total Problems and externalizing scores. The interactions were due to girls with greater obesity reduction showing greater improvement in Total Problems, whereas boys with greater obesity reduction showed less improvement in externalizing problems. These results highlight the multidimensional nature of psychosocial functioning in obese children and call attention to multiple avenues for intervention to improve their psychosocial functioning.

Language Growth in Children With Expressive Language Delay

Developmental expressive language disorder is a frequently occurring condition in children, characterized by severe delay in the development of expressive language compared with receptive language and cognitive skills. Opinions differ regarding whether expressive language delay is a disorder worthy of active intervention or an indication of normal variation in the onset of expressive language. The purpose of this research was to follow for 5 months 26 2-year-old children in whom expressive language disorder had been carefully diagnosed to discover the rate of improvement and its predictors. Improvement was variable, with approximately one third of the children showing no improvement, one third showing mild improvement, and one third in the normal range at posttest. Nearly two thirds of the variance in improvement could be accounted for by three child variables measured by the pretest: parentally reported vocabulary size, parentally reported problems with having regular meals, and observed frequency of quiet activity not requiring the parent's management. A screening procedure involving only one of those variables, reported vocabulary size, was 81% accurate in identifying children's improvement status. The implications of these results for the management of children with expressive language disorder are discussed.

Validity and Therapeutic Efficacy of Individual Patient Goal Attainment Procedures in a Chronic Pain Treatment Center

A sample of 180 patients treated at The Boulder Pain Control Center was randomly chosen to participate in Goal Attainment Scaling (GAS). Of these participants, a total of 76 returned for a 6-month follow-up assessment. Data from these patients were used for two studies: (a) a study of the construct validity of the GAS as a treatment outcome measure, and (b) an assessment of treatment efficacy using the GAS. For the first study, Rao's canonical factor analysis was used to judge the construct validity of the GAS scores. There is moderate statistical evidence to show that GAS can add to our understanding of the structure of pain treatment outcome measures. For the second study, a simple comparison of the treatment group (n = 76) with a control group (n = 129) on several functional, verbal, and sociocultural outcome measures showed that GAS participation accounted for 24.7% of the variance in improvement after treatment.