1,720,981 research outputs found
Upper bound estimators of the population size based on ordinal models for capture-recapture experiments
Full text linkCapture-recapture studies have attracted a lot of attention over the past few decades, especially in applied disciplines where a direct estimate for the size of a population of interest is not available. Epidemiology, ecology, public health, and biodiversity are just a few examples. The estimation of the number of unseen units has been a challenge for theoretical statisticians, and considerable progress has been made in providing lower bound estimators for the population size. In fact, it is well known that consistent estimators for this cannot be provided in the very general case. Considering a case where capture-recapture studies are summarized by a frequency of frequencies distribution, we derive a simple upper bound of the population size based on the cumulative distribution function. We introduce two estimators of this bound, without any specific parametric assumption on the distribution of the observed frequency counts. The behavior of the proposed estimators is investigated using several benchmark datasets and a large-scale simulation experiment based on the scheme discussed by Pledger
Postfazione al volume "Dati e metodi per la statistica giudiziaria"
No full textLa postfazione analizza la portata delle statistiche giudiziarie sul piano della valutazione giuridico sociale dell'efficienza del servizio-giustizia , in cui occorre mediare l'approfondimento delle singole questioni, ed i carichi complessivi di lavoro, in un trade off quali quantitativ
Population Size Estimation Using Multiple Incomplete Lists with Overcoverage
Full text linkThe quantity and quality of administrative information available to National Statistical Institutes have been constantly increasing over the past several years. However, different sources of administrative data are not expected to each have the same population coverage, so that estimating the true population size from the collective set of data poses several methodological challenges that set the problem apart from a classical capture-recapture setting. In this article, we consider two specific aspects of this problem: (1) misclassification of the units, leading to lists with both overcoverage and undercoverage; and (2) lists focusing on a specific subpopulation, leaving a proportion of the population with null probability of being captured. We propose an approach to this problem that employs a class of capturerecapture methods based on Latent Class models. We assess the proposed approach via a simulation study, then apply the method to five sources of empirical data to estimate the number of active local units of Italian enterprises in 2011
Respiratory Tract Infections in Inflammatory Bowel Disease Patients Taking Vedolizumab: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Full text linkThe ongoing COVID-19 pandemic has raised concerns about the risk of SARS-CoV-2 infection in patients with Crohn's disease (CD) and patients with ulcerative colitis (UC) taking immunosuppressants or biologics. We conducted a systematic review and meta-analysis to assess the risk of respiratory infections in patients with inflammatory bowel disease (IBD) treated with vedolizumab. We searched PubMed, EMBASE and Scopus to identify randomized controlled trials (RCT) comparing vedolizumab to placebo in patients with IBD. Outcomes were the rate of respiratory tract infections (RTI), upper respiratory tract infections (URTI) and lower respiratory tract infections (LRTI) among patients receiving vedolizumab as compared with placebo. Pooled rates were reported as Odds Ratios (OR) with 95% Confidence Interval (CI). Eight RCT involving 3,287 patients (1873 CD and 1415 UC) were analyzed; 2,493 patients received vedolizumab and 794 received placebo. The rates of RTI and URTI were statistically higher in vedolizumab-treated patients compared to placebo [OR = 1.63; 95% CI (1.07-2.49); OR = 1.64 95% CI (1.07-2.53) respectively]. UC patients, but not CD patients, receiving vedolizumab had a higher risk to develop RTI and URTI [OR = 1.98; 95% CI (1.41-2.77); OR = 2.02; 95% CI (1.42-2.87)] compared to placebo-treated patients. The number of LRTI was small in both treatment groups. Data confirm the good safety profile of vedolizumab even though RTI were more frequent in patients receiving vedolizumab and the risk of URTIs was significantly higher in patients with UC
Cava Pralongo. Nuove segnalazioni dalle pegmatiti della Valle del Vanoi (Canal San Bovo, Trento).
No full textCava Pralongo. Nuove segnalazioni dalle pegmatiti della Valle del Vanoi (Canal San Bovo, Trento)
A latent class approach for allocation of employees to local units
No full textIn 2011, the Italian Business Register has been reshaped as a database of single workers microdata. Determining the workplace of each individual provides the National Statistical Institute (NSI) with huge information potential. Unfortunately, the administrative sources at our disposal do not always allow a reliable determination of the workplace of each worker. We present a probabilistic methodology to assign a workplace to each employee by assigning him to one of the local units of the enterprise he works for. We used a Latent Class Model to estimate the probability of each employee to belong to each local unit. We assumed the total number of employees per local unit as a constraint. A computationally intensive optimization problem has been solved for each of the ca. 200 thousands multilocated enterprises. The results refer to year 2011
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