Multivariate generalized linear mixed models for continuous bounded outcomes: Analyzing the body fat percentage data

2021 ◽  
pp. 096228022110432
Author(s):  
Ricardo R Petterle ◽  
Henrique A Laureano ◽  
Guilherme P da Silva ◽  
Wagner H Bonat
Keyword(s):  
Maximum Likelihood ◽  
Body Fat ◽  
The Body ◽  
Model Parameters ◽  
Body Fat Percentage ◽  
Fat Percentage ◽  
Data Set ◽  
Proposed Model ◽  
Computational Implementation ◽  
The Impact

We propose a multivariate regression model to handle multiple continuous bounded outcomes. We adopted the maximum likelihood approach for parameter estimation and inference. The model is specified by the product of univariate probability distributions and the correlation between the response variables is obtained through the correlation matrix of the random intercepts. For modeling continuous bounded variables on the interval [Formula: see text] we considered the beta and unit gamma distributions. The main advantage of the proposed model is that we can easily combine different marginal distributions for the response variable vector. The computational implementation is performed using Template Model Builder, which combines the Laplace approximation with automatic differentiation. Therefore, the proposed approach allows us to estimate the model parameters quickly and efficiently. We conducted a simulation study to evaluate the computational implementation and the properties of the maximum likelihood estimators under different scenarios. Moreover, we investigate the impact of distribution misspecification in the proposed model. Our model was motivated by a data set with multiple continuous bounded outcomes, which refer to the body fat percentage measured at five regions of the body. Simulation studies and data analysis showed that the proposed model provides a general and rich framework to deal with multiple continuous bounded outcomes.

scholarly journals Maximum Likelihood Estimation of the VAR(1) Model Parameters with Missing Observations

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Helena Mouriño ◽  
Maria Isabel Barão
Keyword(s):  
Stochastic Process ◽  
Missing Data ◽  
Maximum Likelihood ◽  
Moving Average ◽  
Practical Importance ◽  
Likelihood Estimation ◽  
Model Parameters ◽  
Missing Observations ◽  
Data Set ◽  
The Impact

Missing-data problems are extremely common in practice. To achieve reliable inferential results, we need to take into account this feature of the data. Suppose that the univariate data set under analysis has missing observations. This paper examines the impact of selecting an auxiliary complete data set—whose underlying stochastic process is to some extent interdependent with the former—to improve the efficiency of the estimators for the relevant parameters of the model. The Vector AutoRegressive (VAR) Model has revealed to be an extremely useful tool in capturing the dynamics of bivariate time series. We propose maximum likelihood estimators for the parameters of the VAR(1) Model based on monotone missing data pattern. Estimators’ precision is also derived. Afterwards, we compare the bivariate modelling scheme with its univariate counterpart. More precisely, the univariate data set with missing observations will be modelled by an AutoRegressive Moving Average (ARMA(2,1)) Model. We will also analyse the behaviour of the AutoRegressive Model of order one, AR(1), due to its practical importance. We focus on the mean value of the main stochastic process. By simulation studies, we conclude that the estimator based on the VAR(1) Model is preferable to those derived from the univariate context.

scholarly journals A Family of Loss Distributions with an Application to the Vehicle Insurance Loss Data

2019 ◽  
pp. 731-744 ◽  
Author(s):  
Zubair Ahmad Ahmad ◽  
Eisa Mahmoudi Mahmoudi ◽  
G. G. Hamedani
Keyword(s):  
Maximum Likelihood ◽  
Financial Risk ◽  
Maximum Likelihood Estimates ◽  
Model Parameters ◽  
Data Set ◽  
Loss Model ◽  
New Class ◽  
Proposed Model ◽  
Loss Distributions ◽  
Loss Data

Actuaries are often in search of nding an adequate loss model in the scenario of actuarial and financial risk management problems. In this work, we propose a new approach to obtain a new class of loss distributions. A special sub-model of the proposed family, called the Weibull-loss model isconsidered in detail. Some mathematical properties are derived and maximum likelihood estimates of the model parameters are obtained. Certain characterizations of the proposed family are also provided. A simulation study is done to evaluate the performance of the maximum likelihood estimators. Finally, an application of the proposed model to the vehicle insurance loss data set is presented.

scholarly journals Is the impact of adiposity on taste perceptions moderated by chronic physical activity? An overview of the data from NHANES 2013-2014.

2021 ◽  
Author(s):  
Alexandre-Charles Gauthier ◽  
Marie-Eve Mathieu
Keyword(s):  
Physical Activity ◽  
Body Fat ◽  
Activity Level ◽  
Body Fat Percentage ◽  
Activity Levels ◽  
Fat Percentage ◽  
Active Lifestyle ◽  
Physical Activity Levels ◽  
Tip Test ◽  
The Impact

Introduction Taste is a key sensory modulator of eating behaviour and thus energy intake. The effects of acute exercise has recently been confirmed especially regarding sweet and salty tastes. Physical activity is a safe and effective countermeasure to certain types of chemosensory losses, especially in older populations. Knowing that taste can be impaired with increased adiposity, it is unknown if the adoption of an active lifestyle on a regular basis can mitigate such impairments. Methods Data were extracted from NHANES 2013-2014 database. Perception of salt and bitter tastes for Tongue Tip Test and Whole Mouth Test, physical activity levels over an 8-9-day period and adiposity were analyzed. Moderation analyses were used to study the impact of adiposity on taste perceptions, with physical activity level as the moderator. Results The 197 participants (130 males) included in this project had a mean+/-standard deviation age of 49.1+/-5.2 years, a mean body fat percentage of 31.7+/-7.6% and mean daily physical activity levels of 11 084+/-3531 Monitor-Independent Movement Summary unit (MIMS). The positive association between adiposity and both bitter Tongue Tip Test and overall result (salt+bitter) of Tongue Tip Test were moderated by the adoption of an active lifestyle, with better taste scores observed in individuals achieving higher physical activity levels. When moderation analysis were stratified by gender, the effect of physical activity was no longer significant. Perspectives This study is the first to evaluate the influence of an active lifestyle on the preservation of some taste perceptions across a wide range of adiposity levels. While differences in taste can be observed regarding body fat percentage, physical activity moderates that relation only when men and women are analysed together.

Ultrasound Measurements of Subcutaneous Fat Thickness Are Robust Against Hydration Changes

2020 ◽  
pp. 1-6
Author(s):  
Dale R. Wagner ◽  
James D. Cotter
Keyword(s):  
Body Composition ◽  
Body Fat ◽  
Subcutaneous Fat ◽  
Hydration Status ◽  
Body Fat Percentage ◽  
Fat Percentage ◽  
Ultrasound Measurements ◽  
Subcutaneous Fat Thickness ◽  
Fat Thickness ◽  
The Impact

Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous fat thickness and estimates of body fat percentage. In a crossover design, 11 adults (27.1 ± 10.5 years) completed dehydration and hyperhydration trials to alter body mass by approximately ±2%. Dehydration was achieved via humid heat (40 °C, 60% relative humidity) with exercise, whereas hyperhydration was via ingestion of lightly salted water. Ultrasound measurements were taken at 11 body sites before and after each treatment. Participants lost 1.56 ± 0.58 kg (−2.0 ± 0.6%) during the dehydration trial and gained 0.90 ± 0.21 kg (1.2 ± 0.2%) during the hyperhydration trial even after urination. The sum of fat thicknesses as measured by ultrasound differed by <0.90 mm across trials (p = .588), and ultrasound estimates of body fat percentage differed by <0.5% body fat. Ultrasound measures of subcutaneous adipose tissue were unaffected by acute changes in hydration status by extents beyond which are rare and overtly self-correcting, suggesting that this method provides reliable and robust body composition results even when subjects are not euhydrated.

EFFECT OF SPORTS MEDICINE ON REDUCING BODY FAT PERCENTAGE AND LEAN BODY MASS

2021 ◽  
Vol 27 (7) ◽  
pp. 714-717
Author(s):  
Chunyan Fan
Keyword(s):  
Aerobic Exercise ◽  
Body Fat ◽  
Exercise Performance ◽  
Performance Indicators ◽  
Sports Medicine ◽  
The Body ◽  
Anaerobic Exercise ◽  
Body Fat Percentage ◽  
Fat Percentage ◽  
Level Of Evidence

ABSTRACT Introduction: Aerobic exercise has begun to be widely recognized as a reasonable means of preventing fat and losing weight. Scholars have confirmed that sports can help the human body lose weight and lose fat. Objective: This article measures the exercise performance indicators of subjects in different body fat percentage groups and studies the relationship between body fat percentage and exercise performance indicators. Methods: The study uses experimental methods to determine the percentage of body fat of the subjects. After physical exercise and aerobic exercise, the volunteers were tested for aerobic capacity indicators. Results: The body fat percentage of physically inactive persons was negatively correlated with aerobic and anaerobic exercise capacity indexes. Conclusion: The mechanism of aerobic exercise in weight loss treatment has the effect of promoting lipolysis and regulating blood lipid metabolism. At the same time, it has a significant influence on the number and activity of fat cells. Level of evidence II; Therapeutic studies - investigation of treatment results.

scholarly journals Body Fat Percentage Prediction Using Intelligent Hybrid Approaches

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yuehjen E. Shao
Keyword(s):  
Body Fat ◽  
Hybrid Models ◽  
The Body ◽  
Single Stage ◽  
Support Vector ◽  
Body Fat Percentage ◽  
Fat Percentage ◽  
Explanatory Variables ◽  
Forecasting Models ◽  
Hybrid Approaches

Excess of body fat often leads to obesity. Obesity is typically associated with serious medical diseases, such as cancer, heart disease, and diabetes. Accordingly, knowing the body fat is an extremely important issue since it affects everyone’s health. Although there are several ways to measure the body fat percentage (BFP), the accurate methods are often associated with hassle and/or high costs. Traditional single-stage approaches may use certain body measurements or explanatory variables to predict the BFP. Diverging from existing approaches, this study proposes new intelligent hybrid approaches to obtain fewer explanatory variables, and the proposed forecasting models are able to effectively predict the BFP. The proposed hybrid models consist of multiple regression (MR), artificial neural network (ANN), multivariate adaptive regression splines (MARS), and support vector regression (SVR) techniques. The first stage of the modeling includes the use of MR and MARS to obtain fewer but more important sets of explanatory variables. In the second stage, the remaining important variables are served as inputs for the other forecasting methods. A real dataset was used to demonstrate the development of the proposed hybrid models. The prediction results revealed that the proposed hybrid schemes outperformed the typical, single-stage forecasting models.

scholarly journals Regulation of the Body Fat Percentage in Developmental-Stage Rats by Methylxanthine Derivatives in a High-Fat Diet

2006 ◽  
Vol 70 (5) ◽  
pp. 1134-1139 ◽  
Author(s):  
Hiroko INOUE ◽  
Kazuo KOBAYASHI-HATTORI ◽  
Yumi HORIUCHI ◽  
Yuichi OISHI ◽  
Souichi ARAI ◽  
...  
Keyword(s):  
Developmental Stage ◽  
Body Fat ◽  
High Fat Diet ◽  
The Body ◽  
Body Fat Percentage ◽  
High Fat ◽  
Fat Percentage
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