scholarly journals Seven rules for simulations in paleobiology

Paleobiology ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Joëlle Barido-Sottani ◽  
Erin E. Saupe ◽  
Tara M. Smiley ◽  
Laura C. Soul ◽  
April M. Wright ◽  
...  

AbstractSimulations are playing an increasingly important role in paleobiology. When designing a simulation study, many decisions have to be made and common challenges will be encountered along the way. Here, we outline seven rules for executing a good simulation study. We cover topics including the choice of study question, the empirical data used as a basis for the study, statistical and methodological concerns, how to validate the study, and how to ensure it can be reproduced and extended by others. We hope that these rules and the accompanying examples will guide paleobiologists when using simulation tools to address fundamental questions about the evolution of life.

2018 ◽  
Author(s):  
Chao Zhang ◽  
Martijn Willemsen ◽  
Daniel Lakens

In this commentary, we re-examine the use of a mouse-tracking method for revealing attribute processing speed difference in dietary self-control (Sullivan et al. 2015; Lim et al., 2018). Through re-analyses of Sullivan et al. (2015)’s data and a simulation study, it can be shown that the attribute-angle correlations in the empirical data, which were used to estimate processing speeds, are attributed primarily to their common correlations with choice. The simulation study further suggests that when we account for the choice-mediated attribute-angle correlations, the data patterns used for supporting the original hypothesis can be produced by implementing a plausible alternative mechanism unrelated to processing speeds. The mouse-tracking method therefore fails to provide clear evidence for processing speed difference as a cognitive mechanism of self-control. Researchers should be cautious when using the mouse-tracking method to estimate attribute processing speeds.


Author(s):  
Robert S. Siegler

My goal in writing this book is to change the agenda of the field of cognitive development. In particular, I want to promote greater attention to the question that I believe is inherently at the core of the field: How do changes in children’s thinking occur? Focusing on change may not sound like a radical departure from current practice, but I believe it is. It will require reformulation of our basic assumptions about children’s thinking, the kinds of questions we ask about it, our methods for studying it, the mechanisms we propose to explain it, and the basic metaphors that underlie our thinking about it. That modifications of all of these types are being proposed as a package is no accident. Just as existing approaches have directed our attention away from the change process, so may new ones lead us to focus squarely on it. This concluding chapter summarizes the kinds of changes in assumptions, questions, methods, mechanisms, and metaphors that I think are needed. My initial decision to write this book was motivated by a growing discomfort with the large gap between the inherent mission of the field—to understand changes in children’s thinking—and most of what we actually have been studying. As I thought about the problem, I came to the conclusion that existing assumptions, methods, and theories acted in a mutually supportive way to make what we typically do seem essential, and to make doing otherwise—that is, studying change directly—seem impossible. Even approaches that proclaimed themselves to be radical departures from traditional theories maintained many fundamental assumptions of those theories. An increasing body of empirical evidence, however, indicates that some of the assumptions are wrong and that the way in which they are wrong has led us to ignore fundamental aspects of development. In this section, I describe prevailing assumptions regarding variability, choice, and change, and propose alternatives that seem more consistent with empirical data and more useful for increasing our understanding of how changes occur.


Author(s):  
Ruth McAreavey

This chapter uses migrants’ experiences of poverty in Northern Ireland to consider the way in which poverty is experienced across transnational boundaries. The research draws from empirical data from Northern Ireland, a place which until relatively recently experienced little in-migration. It begins by considering the meaning of poverty and how it is understood transnationally i.e. across national boundaries. The chapter proceeds by showing how migrants shift their framing of poverty according to different circumstances. Poverty is also shown to bring with it physical and emotional vulnerabilities and can cause anxiety, indignity and insecurity for the individuals involved. Finally, the chapter highlights the importance of third party support from the sending or receiving society for overcoming the consequences of poverty.


2016 ◽  
Vol 27 (2) ◽  
pp. 552-569 ◽  
Author(s):  
Rafay Ishfaq ◽  
Uzma Raja ◽  
Shashank Rao

Purpose – The purpose of this paper is to evaluate the interaction between inventory availability (scarcity) and pricing levels (price-leadership (PL)), and its effect on product returns in the internet retail supply chain. Specifically, this paper investigates how supply chain managers can use inventory (seller-induced scarcity) and pricing (PL) levers to control product returns. Design/methodology/approach – Empirical data of sales and product returns from an internet retailer is analyzed to identify the scale of the effect that product scarcity and PL has on product returns. These factors are considered in developing a sales-return process model which is used with empirical data in a simulation study. The study evaluates changes in product returns for different policy settings related to PL and inventory levels. Findings of the simulation study are validated using statistical analysis of empirical data. Findings – PL and seller-induced product scarcity affect the rate of product returns; however, the scale of this effect depends on inventory and pricing decisions. The results identify an inflection boundary based on scarcity and PL levels which reverses this effect. This reversal is explained by underlying principles at play regarding buyers’ valuation of the sale and corresponding product attributes. Practical implications – Supply chain managers in internet retail can leverage lower inventory under the seller-induced scarcity approach to improve revenues. However, reducing inventory levels beyond a threshold is counterproductive, due to an associated increase in product returns. Similarly, setting market competitive prices (PL) can help reduce product returns. Under the seller-induced scarcity condition, this effect is reversed for inventory levels below a threshold. Retailers can implement the methodology developed in this paper to identify the inventory-price threshold that can help increase revenues while keeping the rate of product returns at a manageable level. Originality/value – This research extends prior work regarding the role of product scarcity and pricing on product returns and develops a deeper understanding of how these factors can be managed to control product returns in the internet retail setting.


2019 ◽  
Author(s):  
James A. R. Marshall

AbstractOptimality analysis has recently been proposed for value-based decision-making, in which decision agents are rewarded by the value of the selected option. This contrasts with psychophysics where decision agents are typically rewarded only if they choose the ‘correct’ or best option. The analysis of optimal policies for value-based decisions raises interesting and surprising parallels with decision rules proposed for accuracy-based decisions in binary and multi-alternative cases, and explains experimentally-observed deviations from rationality. However, the analysis assumes that decision agents should treat time as a linear cost, and thus optimise their Bayes Risk from decisions. A more naturalistic assumption is that future rewards are geometrically discounted, since they are less likely to be realised in an uncertain world. Changing the way in which time is costed leads to substantive changes in the resulting optimal policies, explains empirical data that previously could not be explained, and makes falsifiable predictions for future experiments.


2006 ◽  
Vol 1 (3) ◽  
Author(s):  
Andrew Wenn

Through the use of dialogue and numerous photographs, this paper explores the socio- technical nature of the seemingly simple act of providing parking spaces for cars. Using empirical data, the analysis reveals a wide variety social and technical artefacts including batteries, clocks, computers, data, economics, engineering compromises, gatekeepers, humans, politics, procedures, standards and so on. All configured into a complex network.As a result of the analysis, we encounter and examine ideas of infrastructure, and socio-technical networks. From this, we develop a simple graphical metaphor that enables us to better understand the heterogeneous nature of such structures.


2020 ◽  
Vol 142 (02) ◽  
pp. 44-49
Author(s):  
Lina Zeldovich

Abstract The world’s 100,000 cargo ships produce about as much carbon emissions as Germany. One of the ways to reduce those emissions (and slash fuel costs) is to borrow a technology from the past and harness wind power. By harnessing advanced simulation tools, engineers have developed promising fuel-saving technologies that do not necessarily resemble the tall masted ships of the past. This article shows how Europe is leading the way.


2017 ◽  
Vol 2017 (96) ◽  
Author(s):  
Svetlana Edygarova

This paper deals with the contemporary Udmurt language which demonstrates extensive influence from Russian. It is misleading, however, to think that a strong influenceof a prestige language in a minority language would indicate a poorer version of the language in question. Despite Udmurt being a living, rich language, the ways in which people use it depends on their sociolinguistic background. Here, empirical data gathered by means of a translation test is used to demonstrate the way in which the informants use the new adnominal function of the Udmurt adverbial case. It is concluded that this use depends on the linguistic background of the individual speaker. In particular, it reflects speakers’ knowledge of different language varieties, such as the standard language, the vernacular and various dialects. It also reflects how speakers have acquired and continue to use these varieties.


Methodology ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 175-184
Author(s):  
Karl Schweizer ◽  
Stefan Troche

Abstract. The paper describes EV scaling for variances of latent variables included in confirmatory factor models. EV-scaled variances can be achieved in two ways: the estimation of variance parameters based on adjusted factor loadings and alternatively the summation of squared factor loadings obtained under the condition that the variance parameter is set equal to one. By definition, the second procedure yields values that are always positive. EV-scaled variances of latent variables show sizes similar to eigenvalues. The outcome of applying this scaling method is demonstrated in empirical data. The results of a simulation study reveal that the outcomes of the two ways virtually always correspond if the data are generated to include the contribution of a latent source. If there is no such source, the exclusion of solutions with negative error variances virtually always leads to correspondence.


Author(s):  
Donald Eugene Canfield

The air we breathe is 21 percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? This book covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. The book guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, the book takes readers on a remarkable journey through the history of the oxygenation of our planet.


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