2,955 research outputs found
The wild bootstrap for multilevel models
No full textIn this paper we study the performance of the most popular bootstrap schemes for multilevel data. Also, we propose a modied version of the wild bootstrap procedure for hierarchical data structures. The wild bootstrap does not require homoscedasticity or assumptions on the distribution of the error processes. Hence, it is a valuable tool for robust inference in a multilevel framework. We assess the nite size performances of the schemes through a
Monte Carlo study. The results show that for big sample sizes it always pays o to adopt an agnostic approach as the wild bootstrap outperforms other techniques
Rehabilitation interventions for improving balance in Parkinson's disease: a narrative review
No full textFrancesco Lena, PhD, Nicola Modugno, Giulio Greco, Monica Torre, Simone Cesarano, Marco Santilli,
Auwal Abdullahi, Giuseppe Giovannico, and Mohammad Etoom
Introduction: Postural instability is one of the latest clinical manifestations
of Parkinson disease. Because of the limited therapeutic effect
of pharmacological therapies, a favorable consideration has now become
toward rehabilitation interventions. Thus, this study aimed to
synthesize literature evidence to summarize the effects of rehabilitation
interventions for improving balance in Parkinson disease.
Materials and Methods:We conducted a narrative reviewof randomizedcontrolled
clinical trials comparing the effects of interventions, control
interventions, and no interventions on balance-related outcomes. A
comprehensive search using the MEDLINE database was conducted
fromJanuary 2000 to September 2021. This reviewincluded the following
causes of balance-related impairments: inability to control body
weight in the base of support, impaired attention and focus on balance,
postural deformities, proprioceptive deficiency, sensory-motor integration,
and coordination disorders, including visual and auditory-motor
coordination.
Results: Twenty randomized-controlled clinical trialswere included in
the review.Various balance-related outcomeswere included. The included
studies focused on the effectiveness of different rehabilitation interventions,
including physical therapy, virtual reality and telerehabilitation,
treadmill training, hydrotherapy, action observation training, balance
and cues training interventions, and cognitive rehabilitation.
Conclusions: The results suggest that most of the included rehabilitation
interventions have promising therapeutic effects in improving balance
in Parkinson disease
A multilevel model with autoregressive components for the analysis of tribal art prices
No full textIn this paper, we introduce a multilevel model specification with time-series components for the analysis of prices of artworks sold at auctions. Since auction data do not constitute a panel or a time series but are composed of repeated cross-sections, they require a specification with items at the first level nested in time-points. Our approach combines the flexibility of mixed effect models together with the predicting performance of time series as it allows to model the time dynamics directly. Model estimation is obtained by means of maximum likelihood through the expectation–maximization algorithm. The model is motivated by the analysis of the first database ethnic artworks sold in the most important auctions worldwide. The results show that the proposed specification improves considerably over classical proposals both in terms of fit and prediction
Sediment organic matter and its nutritional quality: a short-term experiment with two exotic bivalve species
No full textThis study was aimed to investigate the role of two exotic bivalves (Ruditapes philippinarum and Musculista senhousia) on the trophic enrichment and the nutritional quality of sediments from the Sacca di Goro (northern Adriatic Sea) through manipulative experiments. The concentrations of sedimentary total organic matter, biopolymeric carbon, carbohydrates, proteins, lipids, and chlorophyll-a were determined through a 64 days-long period. The experimental setup consisted in three replicated treatments (R. philippinarum, M. senhousia and simply sand), with treatments and time as fixed factors. All the biochemical classes showed wide fluctuation, and significant differences among treatments were detected during the experimental period. Both bivalve species played a role in sediment enrichment process. At the end of the experimental period, proteins represented the main biochemical class of organic compounds in the treatments with bivalves (48.5 and 44.5% of the biopolymeric fraction in the M. senhousia and R. philippinarum treatments, respectively), while in the control treatment they were only 32.7%. The accumulation of proteic nitrogen increased the nutritional quality of the sedimentary organic matter. Moreover, the presence of M. senhousia also enhanced the accumulation of microphytobenthic carbo
A Multilevel Model with Time Series Components for the Analysis of Tribal Art Prices
No full textIn the present work, we extend the classic multilevel model to include time series components at the second level. In order to show its potentials, we perform an econometric analysis of the Tribal art market. In literature, art prices are modelled through the hedonic regression model, a classic fixed-effect model. We use, instead, a multilevel model for the analysis of Tribal art prices that takes into account the influence of time on artwork prices. Since we do not have repeated measurements of the same items over time, we propose to treat the data as two-level structured in that items are grouped in time points. Hence, the proposed model copes with the time dependence of random effects
A multilevel model for repeated cross-sectional data with stochastic volatility
No full textIn this paper we propose a multilevel approach for the analysis of repeated
cross-sectional data that exhibit volatility effects. We treat individuals as clustered
within time-points so that the dynamics over time is modelled at the second level.
Items sold in auction present a structure like that of repeated cross-sectional surveys
since different goods are sold at different time-points. For prices of artworks, as well
as for other assets (financial, insurance, etc.) the hypothesis of constant volatility appears
unreasonable. In this work we combine a multilevel model with autoregressive
random effects and a stochastic volatility model in order to account for the kurtosis
and the volatility pattern of prices. We apply the model to Tribal art auction prices
and show improvement over existing proposals both in terms of fit and forecastin
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
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