Search results for "Sample Size"

Statistical properties of the site-frequency spectrum associated with lambda-coalescents.

2013

Abstract Statistical properties of the site-frequency spectrum associated with Λ-coalescents are our objects of study. In particular, we derive recursions for the expected value, variance, and covariance of the spectrum, extending earlier results of Fu (1995) for the classical Kingman coalescent. Estimating coalescent parameters introduced by certain Λ-coalescents for data sets too large for full-likelihood methods is our focus. The recursions for the expected values we obtain can be used to find the parameter values that give the best fit to the observed frequency spectrum. The expected values are also used to approximate the probability a (derived) mutation arises on a branch subtending a…

Normalizing the eating pattern with virtual reality for bulimia nervosa: a case report

2015

AbstractThe aim of the present study was to analyze the effects of a virtual reality (VR) component as a therapeutic tool to normalize eating patterns, as part of the cognitive-behavioral treatment of a bulimia nervosa (BN) patient. Results indicated that the patient made significant progress with her eating habits; binges and vomits were eliminated completely. Moreover, when the VR started the patient avoided food, especially meat (5 over 5), and it was reduction of this avoidance in the lasts sessions (2 and 3 over 5). It was also observed a reduction in the avoidance and the fear of eating (from 10 and 9 to 6 and 5 respectively) and increased the impulse control (from 2 to 7). The patien…

Chronic obstructive lung disease “expert system”: Validation of a predictive tool for assisting diagnosis

2018

Purpose: The purposes of this study were development and validation of an expert system (ES) aimed at supporting the diagnosis of chronic obstructive lung disease (COLD). Methods: A questionnaire and a WebFlex code were developed and validated in silico. An expert panel pilot validation on 60 cases and a clinical validation on 241 cases were performed. Results: The developed questionnaire and code validated in silico resulted in a suitable tool to support the medical diagnosis. The clinical validation of the ES was performed in an academic setting that included six different reference centers for respiratory diseases. The results of the ES expressed as a score associated with the risk of su…

Health-related quality of life after bariatric surgery: a systematic review of prospective long-term studies

2014

Author´s accepted manuscript Impaired health-related quality of life (HRQoL) is common in bariatric surgery candidates and is often one of the motivating factors for seeking bariatric surgery. Although many studies have reported changes in HRQoL after bariatric surgery, few are long-term prospective studies and no systematic review has been conducted. A systematic database search identified studies reporting HRQoL preoperatively and ≥ 5 years after bariatric surgery. Change in HRQoL over time was the outcome variable, divided into primary and secondary outcomes. Seven prospective cohort studies met the inclusion criteria. Eight HRQoL measures and six surgical methods were identified. Longte…

The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns

2011

Contains fulltext : 96439.pdf (Publisher’s version ) (Open Access) BACKGROUND: The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with the combined type of attention deficit/hyperactivity disorder (ADHD-CT) and 1446 'unselected' siblings. The aim was to analyse the IMAGE sample with respect to demographic features (gender, age, family status, and recruiting centres) and psychopathological characteristics (diagnostic subtype, symptom frequencies, age at symptom detection, and com…

Chemical separation and MC-ICPMS analysis of U, Th, Pa and Ra isotope ratios of carbonates

2018

Diagenetic alteration of fossil reef corals may have severe effects on the reliability of 230Th/U-ages. The widely applied criteria introduced to test for the reliability of coral 230Th/U-ages are often not sufficient to identify all altered ages. The combination of 230Th/U- with 231Pa/U-dating has been suggested as a promising method to identify altered ages. Furthermore, 226Ra/230Th ratios can provide information about the diagenetic history during the last 10 000 years. Here we present a method to chemically separate U, Th, Pa and Ra from the same aliquot of a carbonate sample. The isotope ratios of our mixed U–Th–Pa–Ra spike are calibrated using a secular equilibrium material treated in…

Limited Usefulness of Capture Procedure and Capture Percentage for Evaluating Reproducibility in Psychological Science

2018

In psychological science, there is an increasing concern regarding the reproducibility of scientific findings. For instance, Replication Project: Psychology (Open Science Collaboration, 2015) found that the proportion of successful replication in psychology was 41%. This proportion was calculated based on Cumming and Maillardet’s (2006) widely employed capture procedure (CPro) and capture percentage (CPer). Despite the popularity of CPro and CPer, we believe that using them may lead to an incorrect conclusion of (a) successful replication when the population effect sizes in the original and replicated studies are different; and (b) unsuccessful replication when the population effect sizes i…

On the Difference between a-priori and observed statistical power - A comment on "statistical power and sample size calculations: A primer for pediat…

2019

SEQUENTIALLY ADJUSTED RANDOMIZATION TO FORCE BALANCE IN CONTROLLED TRIALS WITH UNKNOWN PREVALENCE OF COVARIATES: APPLICATION TO ALCOHOLISM RESEARCH

2005

In treatment outcome studies with small to medium sample sizes (n200), the balance of groups with regard to important factors, which sometimes occur at low prevalence, is indispensable for adequate interpretation. This study tested a method for use in clinical alcoholism research, an uncomplicated procedure for satisfactory randomization of patients to different treatments, taking into account relevant background variables.An easily applicable modification of Efron's biased coin method for the randomization of treatments within strata of unknown but low prevalence was compared with the original approach and alternative methods by computer simulation (10,000 runs). An application example for…

Estimating soil loss of given return period by USLE-M-type models

2020

Many field investigations have clearly shown that rare and severe events control total soil erosion occurring over a long time period with up to 92% of total soil erosion over a 7‐year period resulting from just three daily events. Therefore, soil conservation strategies should be developed taking into account large events rather than long‐term average erosion. From an engineering point of view, establishing the soil loss of a given return period is needed. This can be obtained by the frequency analysis of soil loss measurements or by suitable soil erosion models. The USLE‐M modified and USLE‐M based are two empirical Universal Soil Loss Equation‐Modified (USLE‐M) type models which were dev…