scholarly journals Predictors of early survival in Soay sheep: cohort-, maternal- and individual-level variation

2005 ◽  
Vol 272 (1581) ◽  
pp. 2619-2625 ◽  
Author(s):  
Owen R Jones ◽  
Michael J Crawley ◽  
Jill G Pilkington ◽  
Josephine M Pemberton
Keyword(s):  
Maternal Age ◽  
Ovis Aries ◽  
Relative Importance ◽  
Level Variation ◽  
Individual Level ◽  
Soay Sheep ◽  
Individual Based Models ◽  
Feral Population ◽  
Early Survival ◽  
The Individual

A demographic understanding of population dynamics requires an appreciation of the processes influencing survival—a demographic rate influenced by parameters varying at the individual, maternal and cohort level. There have been few attempts to partition the variance in demography contributed by each of these parameter types. Here, we use data from a feral population of Soay sheep ( Ovis aries ), from the island of St Kilda, to explore the relative importance of these parameter types on early survival. We demonstrate that the importance of variation occurring at the level of the individual, and maternally, far outweighs that occurring at the cohort level. The most important variables within the individual and maternal levels were birth weight and maternal age class, respectively. This work underlines the importance of using individual based models in ecological demography and we, therefore, caution against studies that focus solely on population processes.

Structural Reliability and Stability of Nonmetric Conjoint Analysis

1982 ◽  
Vol 19 (2) ◽  
pp. 199-207 ◽  
Author(s):  
Naresh K. Malhotra
Keyword(s):  
Conjoint Analysis ◽  
Structural Reliability ◽  
Standard Errors ◽  
Relative Importance ◽  
Substantial Variation ◽  
Individual Level ◽  
Structural Perturbation ◽  
Estimated Parameters ◽  
Treatment Conditions ◽  
The Individual

Structural reliability and stability of nonmetric conjoint analysis are examined under conditions of severe structural perturbation and substantial variation in the number of stimulus profiles. The individual-level part worth functions are jackknifed. The jackknifed parameters, derived relative importance weights, and standard errors of estimated parameters are examined across the different treatment conditions. The results indicate that conjoint analysis is a fairly robust procedure for assessing an individual's preferences.

scholarly journals Testing, tracing and isolation in compartmental models

2021 ◽  
Vol 17 (3) ◽  
pp. e1008633
Author(s):  
Simone Sturniolo ◽  
William Waites ◽  
Tim Colbourn ◽  
David Manheim ◽  
Jasmina Panovska-Griffiths
Keyword(s):  
Computational Cost ◽  
Disease Outbreaks ◽  
Population Level ◽  
Compartmental Models ◽  
Contact Tracing ◽  
Adaptive Planning ◽  
Agent Based ◽  
Individual Level ◽  
Individual Based Models ◽  
The Individual

Existing compartmental mathematical modelling methods for epidemics, such as SEIR models, cannot accurately represent effects of contact tracing. This makes them inappropriate for evaluating testing and contact tracing strategies to contain an outbreak. An alternative used in practice is the application of agent- or individual-based models (ABM). However ABMs are complex, less well-understood and much more computationally expensive. This paper presents a new method for accurately including the effects of Testing, contact-Tracing and Isolation (TTI) strategies in standard compartmental models. We derive our method using a careful probabilistic argument to show how contact tracing at the individual level is reflected in aggregate on the population level. We show that the resultant SEIR-TTI model accurately approximates the behaviour of a mechanistic agent-based model at far less computational cost. The computational efficiency is such that it can be easily and cheaply used for exploratory modelling to quantify the required levels of testing and tracing, alone and with other interventions, to assist adaptive planning for managing disease outbreaks.

Individual-based models

2021 ◽  
pp. 213-228
Author(s):  
Viktoriia Radchuk ◽  
Stephanie Kramer-Schadt ◽  
Uta Berger ◽  
Cédric Scherer ◽  
Pia Backmann ◽  
...  
Keyword(s):  
Research Question ◽  
Plant Defence ◽  
Population Cycles ◽  
Population Level ◽  
Adaptive Behaviour ◽  
Heterogeneous Environments ◽  
Individual Level ◽  
Intraspecific Trait Variation ◽  
Individual Based Models ◽  
The Individual

Individual-based models (IBMs, also known as agent-based models) are mechanistic models in which demographic population trends emerge from processes at the individual level. IBMs are used instead of more aggregated approaches whenever one or more of the following aspects are deemed too relevant to be ignored: intraspecific trait variation, local interactions, adaptive behaviour, and response to spatially and temporally heterogeneous environments, which often results in nonlinear feedbacks. IBMs offer a high degree of flexibility and therefore vary widely in structure and resolution, depending on the research question, system under investigation, and available data. Data used to parameterise an IBM can be divided into two categories: species and environmental data. Unlike other model types, qualitative empirical knowledge can be taken into account via probabilistic rules. IBM flexibility is often associated with higher number of parameters and hence higher uncertainty; therefore sensitivity analysis and validation are extremely important tools for analysing these models. The chapter presents three examples: a vole–mustelid model used to understand the mechanisms underlying population cycles in rodents; a wild boar–virus model to study persistence of wildlife diseases in heterogeneous landscapes; and a wild tobacco-moth caterpillar model to study emergence of delayed chemical plant defence against insect herbivores. These examples demonstrate the ability of IBMs to decipher mechanisms driving observed phenomena at the population level and their role in planning applied conservation measures. IBMs typically require more data and effort than other model types, but rewards in terms of structural realism, understanding, and decision support are high.

scholarly journals Individual- and company level determinants of vocational rehabilitation: a multilevel study

2019 ◽  
Vol 29 (Supplement_4) ◽  
Author(s):  
M Laaksonen ◽  
J Rantala ◽  
J Liukko ◽  
A Polvinen ◽  
J Varis ◽  
...  
Keyword(s):  
Social Class ◽  
Vocational Rehabilitation ◽  
Sickness Absence ◽  
Work Disability ◽  
Musculoskeletal Diseases ◽  
Level Variation ◽  
Individual Level ◽  
Explanatory Variables ◽  
Older Employees ◽  
The Individual

Abstract Backround Vocational rehabilitation (VR) is considered an important means to combat work ability problems and enable people to continue working despite health problems. We examined the magnitude of company level variation in VR and determined which individual- and company level characteristics are associated with access to VR due to mental disorders, musculoskeletal diseases, and other somatic diseases. Methods A 30% random sample of all Finnish private sector companies with more than 10 employees aged 25-62 years at the end of 2010 (5.567 companies with 300.601 employees) was followed up for incident VR for six years. Company size and industry, as well as gender, age, education, social class and sickness absence measured both at the individual- and company level, were used as explanatory variables in multilevel logit models. Results After controlling for the individual level covariates, companies accounted for 12% of the variance in VR. The proportion was largest in VR due to musculoskeletal diseases. VR was more common among women, older employees (except the very oldest age group), those with low education (particularly due to musculoskeletal diseases), low social class, and previous sickness absence. VR was more common in larger companies, and in construction and in health and social work, and less common in professional activities. VR was more common in companies with low proportion of highly educated employees and with higher sickness absence rates. Conclusions Company level variation in VR was substantial after controlling for individual level characteristics of the employees. The employer may have an important role in the prevention of work disability through vocational rehabilitation. Key messages Company level variation in vocational rehabilitation was substantial after controlling for individual level characteristics of the employees. The employer may have an important in the prevention of work disability through vocational rehabilitation.

scholarly journals Simplex: An individual-based platform for ecological modeling

2015 ◽  
Author(s):  
Kenneth J Locey
Keyword(s):  
Simulated Data ◽  
Ecological Modeling ◽  
Unit Testing ◽  
State Variables ◽  
Community Based ◽  
Individual Level ◽  
Resource Limited ◽  
Individual Based Models ◽  
Ecological Patterns ◽  
The Individual

A popular approach in ecological modeling explicitly simulates the biology and ecology of individual organisms. Individual-based models (IBM) allow ecological patterns and dynamics to be studied as they emerge from the individual level according to simulated principles and theories. IBMs also allow virtually any aspect of a simulated system to be tracked and recorded for later analysis. I developed a novel IBM platform (i.e, simplex) to explicitly simulate physiology, life history, resource-limited growth, fluctuating environmental dynamics, and community assembly and structure in both fluid and non-fluid environments. simplex accomplishes three primary tasks in keeping with its namesake (i.e., a generalized notion of a triangle to arbitrary dimensions). First, simplex assembles and runs stochastic ecological models from random combinations of over 20 state variables. Second, simplex stores the output of models and generates and stores animations. Third, simplex provides R Markdown files for analyzing simulated data. The simplex source code is freely available, includes the standard ODD description protocol, is open to community-based revision, includes unit testing and time testing, and has been developed to run on modest hardware.

scholarly journals The Relative Impact Of Public Information In Shaping Investor Expectations

2011 ◽  
Vol 25 (2) ◽  
Author(s):  
John E. Burnett ◽  
Carolyn Carroll ◽  
Paul Thistle
Keyword(s):  
Empirical Studies ◽  
Public Information ◽  
Relative Impact ◽  
Relative Importance ◽  
Additional Insight ◽  
Individual Level ◽  
Risk Return ◽  
News Announcements ◽  
The Individual ◽  
Underlying Risk

<p class="MsoNormal" style="text-align: justify; margin: 0in 0.5in 0pt; mso-hyphenate: none;"><span style="font-family: &quot;Times New Roman&quot;,&quot;serif&quot;; letter-spacing: -0.1pt; font-size: 10pt;">Empirical studies at the individual level (event studies) and those using more general measures of information and/or aggregate price movements often yield somewhat conflicting results regarding the relative importance of public information.<span style="mso-spacerun: yes;">&nbsp; </span>Employing a more focused methodology that begins with no prior limitations on the number and types of public news announcements that may affect the underlying risk-return relationship, we are able to offer additional insight regarding the relative impact of public information.<span style="mso-spacerun: yes;">&nbsp; </span>We find that approximately two-thirds of the changes can be associated with the arrival of public information.<span style="mso-spacerun: yes;">&nbsp; </span>While, in general, this is a stronger link than previously found, it is a weaker link than expected; leading us to conclude that factors other than public information clearly play an important role.<span style="mso-spacerun: yes;">&nbsp; </span>We also provide new results on the relative importance of different information types, and on correlates (such as firm size) of the effect of information.</span></p>

Self-interest, partisanship, and the conditional influence of taxation on support for war in the USA

2015 ◽  
Vol 35 (1) ◽  
pp. 43-64 ◽  
Author(s):  
Douglas Kriner ◽  
Breanna Lechase ◽  
Rosella Cappella Zielinski
Keyword(s):  
Public Support ◽  
Policy Preferences ◽  
Level Variation ◽  
Individual Level ◽  
The Public ◽  
Self Interest ◽  
Survey Experiments ◽  
Negative Effect ◽  
The Usa ◽  
The Individual

Does the imposition of taxation inevitably erode public support for war? Through a pair of survey experiments we show that whether a war tax decreases public support for military action critically depends on the design of the taxation instrument itself. Broad-based, regressive taxes decrease support for war; progressive taxes targeted on the wealthy do not. We also uncover the mechanisms through which Americans incorporate information about war taxation into their wartime policy preferences. Economic self-interest, alone, cannot explain the individual-level variation in reactions to war taxation. Rather, Americans assess war taxation both through the lens of economic self-interest and by using partisan heuristics. The negative effect of taxation on war support is both conditional on the design of the taxation instrument and variable across segments of the public.

Policy Direction and Performance Evaluation: Complementary Explanations of the Reagan Elections

1990 ◽  
Vol 20 (2) ◽  
pp. 143-235 ◽  
Author(s):  
J. Merrill Shanks ◽  
Warren E. Miller
Keyword(s):  
Ronald Reagan ◽  
Relative Importance ◽  
Comprehensive Model ◽  
Direct And Indirect Effects ◽  
Individual Level ◽  
The Us ◽  
And Performance ◽  
Policy Direction ◽  
The Individual ◽  
Presidential Performance

This article reviews the range of explanations which have been proposed for voting behaviour in the US elections won by Ronald Reagan and develops a comprehensive model for the evolution of electoral choices in both of those contests. Estimates are provided for both the direct and indirect effects of several types of variables or ‘explanatory themes’, and those estimates are used to assess the relative importance of each of those themes in explaining individual-level choices and the aggregate outcomes of both Reagan elections. These procedures suggest that preferences concerning both policy direction and evaluations of national and presidential performance played major roles in the two Reagan elections – both in the individual-level decisions and in producing the Republicans' aggregate victories.

scholarly journals simplex: An individual-based platform for ecological modeling

2015 ◽  
Author(s):  
Kenneth J Locey
Keyword(s):  
Simulated Data ◽  
Ecological Modeling ◽  
Unit Testing ◽  
State Variables ◽  
Community Based ◽  
Individual Level ◽  
Resource Limited ◽  
Individual Based Models ◽  
Ecological Patterns ◽  
The Individual

A popular approach in ecological modeling explicitly simulates the biology and ecology of individual organisms. Individual-based models (IBM) allow ecological patterns and dynamics to be studied as they emerge from the individual level according to simulated principles and theories. IBMs also allow virtually any aspect of a simulated system to be tracked and recorded for later analysis. I developed a novel IBM platform (i.e, simplex) to explicitly simulate physiology, life history, resource-limited growth, fluctuating environmental dynamics, and community assembly and structure in both fluid and non-fluid environments. simplex accomplishes three primary tasks in keeping with its namesake (i.e., a generalized notion of a triangle to arbitrary dimensions). First, simplex assembles and runs stochastic ecological models from random combinations of over 20 state variables. Second, simplex stores the output of models and generates and stores animations. Third, simplex provides R Markdown files for analyzing simulated data. The simplex source code is freely available, includes the standard ODD description protocol, is open to community-based revision, includes unit testing and time testing, and has been developed to run on modest hardware.

Differential Effects of Competence and Morality on Self-Esteem at the Individual and the Collective Level

2020 ◽  
Vol 51 (3) ◽  
pp. 183-198
Author(s):  
Wiktor Soral ◽  
Mirosław Kofta
Keyword(s):  
Self Esteem ◽  
Differential Effects ◽  
Individual Level ◽  
The Subject ◽  
The Individual

Abstract. The importance of various trait dimensions explaining positive global self-esteem has been the subject of numerous studies. While some have provided support for the importance of agency, others have highlighted the importance of communion. This discrepancy can be explained, if one takes into account that people define and value their self both in individual and in collective terms. Two studies ( N = 367 and N = 263) examined the extent to which competence (an aspect of agency), morality, and sociability (the aspects of communion) promote high self-esteem at the individual and the collective level. In both studies, competence was the strongest predictor of self-esteem at the individual level, whereas morality was the strongest predictor of self-esteem at the collective level.

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