Calculating Utility Decrements Associated With an Adverse Event

Background: When calculating the decreases in health utility associated with adverse events, often a number ofrespondents achieve the upper utility bound of 1. “Marginal” Tobit or CLAD coefficients have been used to account for this. These are calculated by using a Tobit or a CLAD model to estimate the decrease in a latent unbounded variable associated with the event or condition, then to multiply by the proportion of respondents falling below 1 in order to transform back to the utility scale. Objective & Methods: Starting with the Tobit model, we show mathematically that this procedure is not valid, when calculating decreases in utility associated with binary events. We then generalize the result to the CLAD model. A selection of published studies is used to illustrate the bias in the marginal Tobit decrements. Results: The degree of bias is more severe the greater the decrease in utility associated with the event, and the larger the proportion of individuals at the upper ceiling.In the examples studied, the degree of bias was often greater than 10%. We provide the correct formula for calculating the utility decrement. Conclusions: The marginal Tobit and CLAD coefficients should not be used as estimates of a utility decrement corresponding to an adverse event or health condition unless the coefficients are small in absolute value, or if the proportion of individuals at the upper utility bound is small. In other settings, the corrected formula or alternative regression methods (e.g. linear models of mean utility) should be considered.

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The impact of the health condition of oaks from the Krotoszyn Plateau on the mechanical properties of timber structures

Folia Forestalia Polonica ◽

10.1515/ffp-2015-0023 ◽

2015 ◽

Vol 57 (4) ◽

pp. 224-232

Author(s):

Jarosław Siwiński ◽

Katarzyna Kubiak ◽

Miłosz Tkaczyk ◽

Anna Mazur ◽

Ryszard Rekucki

Keyword(s):

Mechanical Properties ◽

Health Condition ◽

Health State ◽

Timber Structures ◽

Strength Parameters ◽

Modified Method ◽

Strength Tests ◽

Prior Selection ◽

The Impact ◽

Selection Of

Abstract The study was conducted to perform a comparative analysis of the mechanical properties of wood samples derived from oaks in the Krotoszyn Plateau, which depend on the health state of the trees. Strength parameters of oak wood were calculated for selected diseased and healthy trees (according to the Roloff classification). The study was conducted by a modified method described in the standard Polish Norm PN EN 408+ A1: 2012. For testing, prior selection of wood samples showed that more wood samples of diseased trees compared with those of healthy oaks did not fulfil the Polish standard requirements. According to the method used, the average results of strength tests of timber structures from healthy oaks exhibited higher strength parameters than those of the diseased trees.

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Criterios y modelos estadísticos de eficacia escolar

Revista de Investigación Educativa ◽

10.6018/rie.417881 ◽

2020 ◽

Vol 38 (2) ◽

pp. 311-327

Author(s):

Luis Lizasoain Hernández

Keyword(s):

Effective Schools ◽

School Effectiveness ◽

Linear Models ◽

Basque Country ◽

Outcome Variable ◽

Multilevel Regression ◽

School Effectiveness Research ◽

Regression Techniques ◽

Pais Vasco ◽

Selection Of

El objetivo de este artículo es presentar los criterios y modelos estadísticos empleados en un estudio de eficacia escolar desarrollado en la Comunidad Autónoma del País Vasco empleando como variable criterio los resultados en matemáticas, comprensión lectora en lengua castellana y en lengua vasca, resultantes de las evaluaciones de Diagnóstico aplicadas en cinco años. Se definen cuatro criterios de eficacia escolar: puntuaciones extremas, residuos extremos, crecimiento de puntuaciones y crecimiento de residuos. Para ello se han aplicado técnicas de regresión multinivel empleando modelos jerárquicos lineales. Los resultados permiten una selección de centros tanto de alta como de baja eficacia que se basa en cuatro enfoques distintos y complementarios de la eficacia (o ineficacia) escolar. The aim of this paper is to present the statistical criteria and models used in a school effectiveness research carried out in the Basque Country Autonomous Community using as outcome variable the mathematics, spanish language and basque language scores. These scores come from the Diagnosis Assessments applied for five years. Four school effectiveness criteria are defined: extreme scores, extreme residuals, scores growth and residuals growth. Multilevel regression techniques have been applied using hierarchical linear models (HLM). Results have permitted a selection of both high and low effective schools based on four different and complementary school effectiveness approaches.

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An investigation of human vs. technology-induced variation in catchability for a selection of European fishing fleets

ICES Journal of Marine Science ◽

10.1093/icesjms/fsr150 ◽

2011 ◽

Vol 68 (10) ◽

pp. 2252-2263 ◽

Cited By ~ 16

Author(s):

Stéphanie Mahévas ◽

Youen Vermard ◽

Trevor Hutton ◽

Ane Iriondo ◽

Angélique Jadaud ◽

...

Keyword(s):

Linear Models ◽

Generalized Additive Models ◽

Technical Information ◽

Fishing Effort ◽

Additive Models ◽

Induced Variation ◽

Fishing Fleets ◽

The Impact ◽

Selection Of ◽

Experience Effect

Abstract Mahévas, S., Vermard, Y., Hutton, T., Iriondo, A., Jadaud, A., Maravelias, C. D., Punzón, A., Sacchi, J., Tidd, A., Tsitsika, E., Marchal, P., Goascoz, N., Mortreux, S., and Roos, D. 2011. An investigation of human vs. technology-induced variation in catchability for a selection of European fishing fleets. – ICES Journal of Marine Science, 68: 2252–2263. The impact of the fishing effort exerted by a vessel on a population depends on catchability, which depends on population accessibility and fishing power. The work investigated whether the variation in fishing power could be the result of the technical characteristics of a vessel and/or its gear or whether it is a reflection of inter-vessel differences not accounted for by the technical attributes. These inter-vessel differences could be indicative of a skipper/crew experience effect. To improve understanding of the relationships, landings per unit effort (lpue) from logbooks and technical information on vessels and gears (collected during interviews) were used to identify variables that explained variations in fishing power. The analysis was undertaken by applying a combination of generalized additive models and generalized linear models to data from several European fleets. The study highlights the fact that taking into account information that is not routinely collected, e.g. length of headline, weight of otter boards, or type of groundrope, will significantly improve the modelled relationships between lpue and the variables that measure relative fishing power. The magnitude of the skipper/crew experience effect was weaker than the technical effect of the vessel and/or its gear.

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Tree-Based Modeling Techniques

Advances in Business Information Systems and Analytics - Machine Learning Techniques for Improved Business Analytics ◽

10.4018/978-1-5225-3534-8.ch001 ◽

2019 ◽

pp. 1-18

Author(s):

Dileep Kumar G.

Keyword(s):

Predictive Models ◽

Data Science ◽

Linear Models ◽

High Accuracy ◽

Gradient Boosting ◽

Regression Methods ◽

Data Analyst ◽

Linear Relationships ◽

Learning Techniques ◽

Modeling Techniques

Tree-based learning techniques are considered to be one of the best and most used supervised learning methods. Tree-based methods empower predictive models with high accuracy, stability, and ease of interpretation. Unlike linear models, they map non-linear relationships pretty well. These methods are adaptable at solving any kind of problem at hand (classification or regression). Methods like decision trees, random forest, gradient boosting are being widely used in all kinds of machine learning and data science problems. Hence, for every data analyst, it is important to learn these algorithms and use them for modeling. This chapter guide the learner to learn tree-based modeling techniques from scratch.

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A 28-years-long monitoring study suggests heavy decline and habitat shifts in three populations of a Mediterranean tortoise species

Animal Biology ◽

10.1163/15707563-bja10014 ◽

2020 ◽

Vol 71 (1) ◽

pp. 21-35

Author(s):

Lorenzo Rugiero ◽

Massimo Capula ◽

Daniele Dendi ◽

Fabio Petrozzi ◽

Massimiliano Di Vittorio ◽

...

Keyword(s):

Habitat Use ◽

Linear Models ◽

Central Italy ◽

Habitat Type ◽

Thermal Ecology ◽

Ecological Studies ◽

Monitoring Study ◽

Testudo Hermanni ◽

Selection Of

Abstract Long-term ecological studies are important for understanding wild populations’ dynamics and processes and the actual factors that can determine their decline. Here, we report the results of a 28-years-long (1992–2019) monitoring of three distinct populations of a tortoise, Testudo hermanni, in Central Italy, with an emphasis on their population abundance trends and on the eventual variation in their habitat use across years and among the study areas. Samplings were conducted by Visual Encounter Survey (VES) methodology, and using a suite of statistical analyses including correlations and Generalized Linear Models analyses. Our data showed a statistically significant decline in tortoise sightings through time, and concurrently also a variation in habitat use by tortoises. In all the three study areas, we observed a significant increase of tortoise sighting frequency in the habitat type characterized by high (>taller than 200 cm) shrubby and wooded vegetation. Since our analyses revealed no significant change in the habitat type availability by year in each study area, we suggest that T. hermanni was increasingly selecting closed vegetation spots throughout the years. We hypothesize that this observed trend of shift in habitat selection could be due to lowering their body temperatures to prevent overheating. So, the selection of more covered spots would be a thermal ecology adaptive consequence of the ongoing global warming.

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Passage rate of solids and fluids in the digestive tract of buffaloes, cattle and sheep: selection of non-linear model

Animal Science ◽

10.1017/s1357729800015551 ◽

1997 ◽

Vol 64 (1) ◽

pp. 63-69 ◽

Cited By ~ 6

Author(s):

A. Amici ◽

S. Bartocci ◽

S. Terramoccia ◽

F. Martillotti

Keyword(s):

Linear Models ◽

Latin Square ◽

Sums Of Squares ◽

Passage Rate ◽

Significant Difference ◽

Age Dependent ◽

Non Linear ◽

Best Fitting ◽

Kinetics Of ◽

Selection Of

AbstractFive mathematical models were compared to select the most satisfactory model to describe digesta kinetics of solids and fluids in the gastrointestinal tract of buffaloes (Mediterranean bulls), cattle (Friesian bulls) and sheep (Delle Langhe rams) given food at maintenance level, according to a Latin-square arrangement for four consecutive periods of 21 days. Chromium mordanted alfalfa hay and cobalt-ethylenediamine tetraacetic acid were used as nonabsorbable markers and were administered through the rumen cannula in a single dose. Four different isonitrogenous diets (N × 6·25 = 140 g/kg dry matter) with different concentrate:forage ratios (12·5:87·5, 25:75, 37·5:62·5, 50:50) were used.Faecal chromium and cobalt concentration curves were fitted with five non-linear models: three gamma (G2, G3, G4) age-dependent one-compartment, one gamma age-dependent/age-independent two-compartment (G2G1) and one multicompartment (MC).Wilcoxon tests on residual sums of squares of the different models for solids showed that MC and G4 gave a better fit than G2G1, G2, G3 for all the data and within the species. The comparison of MC v. G4 did not show any significant difference (P > 0·05) for all the data computed together or within each species. Nevertheless, MC had a higher number of curves with lower residual sums of squares in comparison with G4 and was also able to produce estimates of digesta kinetics in the second compartment.The cobalt excretion curves for fluids, considering all the data, and only within sheep, showed G4 as the best fitting model. When G4 was compared with other models no significant differences were recorded either for cattle: G4 v. G2 (F = 0·6645), G4 v. G2G1 (P = 0·0620) and for buffalo: G4 v. G2 (P = 0·1575), G4 v.G3(P = 0·0796) and G4 v. G2G1 (P = 0·1641).It is concluded that the multicompartment model (MC) and G4 model were the best fits for solids and for fluids respectively.

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Vibration Based Condition Monitoring of Helicopter Gearboxes Based on Cyclostationary Analysis

Volume 6: Ceramics; Controls, Diagnostics, and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2019-91150 ◽

2019 ◽

Cited By ~ 1

Author(s):

Alexandre Mauricio ◽

Linghao Zhou ◽

David Mba ◽

Konstantinos Gryllias

Keyword(s):

Experimental Tests ◽

Operational Reliability ◽

Health Condition ◽

Operating Conditions ◽

False Alarms ◽

Complex Structures ◽

Planetary Gearbox ◽

Bearing Defects ◽

Envelope Spectrum ◽

Selection Of

Abstract The core of a helicopter drivetrain is a complex planetary main gearbox (MGB) which reduces the high input speed generated by the engines in order to provide the appropriate torque to the main rotors and to other auxiliary systems. The gearbox consists of various shafts, planetary gears and bearings and operates under varying conditions under excessive friction, heat and high mechanical forces. The components are vulnerable to fatigue defects and therefore Health and Usage Monitoring Systems (HUMS) have been developed in order to monitor the health condition of the gearbox, focusing towards early, accurate and on time fault detection with limited false alarms and missed detections. The main aim of a HUM System is by health monitoring to enhance the helicopters’ operational reliability, to support the maintenance decision making, and to reduce the overall maintenance costs. The importance and the need for more advanced and accurate HUMS have been emphasized recently by the post-accident analysis of the helicopter LN-OJF, which crashed in Norway in 2016. During the last few decades various methodologies and diagnostic indicators/features have been proposed for the monitoring of rotating machinery operating under steady conditions but still there is no global solution for complex structures. A new tool called IESFOgram has been recently proposed by the authors, based on Cyclostationary Analysis, focusing on the accurate selection of a filtering band, under steady and varying speed conditions. Moreover the Cyclic Spectral Coherence is integrated along the selected frequency band leading to an Improved Envelope Spectrum. In this paper the performance of the tool is tested on a complex planetary gearbox, with several vibration sources. The method is tested, evaluated and compared to state of the art methods on a dataset captured during experimental tests under various operating conditions on a Category A Super Puma SA330 main planetary gearbox, presenting seeded bearing defects of different sizes.

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DOES MEMORY CARE MATTER? EXAMINING THE EFFECT OF DEMENTIA-LICENSED CARE ON RESIDENTS’ OUTCOMES

Innovation in Aging ◽

10.1093/geroni/igz038.2008 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

pp. S545-S546

Author(s):

Portia Y Cornell ◽

Momotazur Rahman ◽

Wenhan Zhang ◽

Kali Thomas

Keyword(s):

Assisted Living ◽

Dementia Care ◽

Emergency Department Utilization ◽

Regression Methods ◽

Home Address ◽

Memory Care ◽

The Difference ◽

Hospice Use ◽

Hospital Days ◽

Selection Of

Abstract The objective of this study is to estimate the effect of receiving care in a dementia-care licensed (DCL) assisted living community, versus a standard AL, on outcomes of residents with ADRD. In four states that issue a license for specialized dementia care (AL, CO, MS, and NY), we identify a cohort of 5,720 Medicare fee-for-services beneficiaries with ADRD who moved to an AL in 2014. To control for unobserved factors that contribute to a patient’s selection of AL type, we use the difference in the log-distances from an individual’s home address to the nearest DCL and standard AL as an instrumental variable. We will report the effect of residence in a DCL AL on mortality, inpatient hospital days, emergency department utilization, and hospice use, showing how the use the distance instrument offers differing estimates from unadjusted or multiple-regression methods.

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