The “Equal Environments Assumption” in MZ-DZ Twin Comparisons: an Untenable Premise of Psychiatric Genetics?

1996 ◽  
Vol 45 (3) ◽  
pp. 349-360 ◽  
Author(s):  
A. Pam ◽  
S.S. Kemker ◽  
C.A. Ross ◽  
R. Golden
Keyword(s):  
Mathematical Model ◽  
Behavioral Genetics ◽  
Empirical Studies ◽  
Heritability Estimate ◽  
Operational Definition ◽  
Psychiatric Genetics ◽  
Equal Environments Assumption ◽  
Definition Of ◽  
Scientific Value ◽  
Equal Environments

AbstractThe comparison of MZ-DZ twins in behavioral genetics has produced what seems like irrefutable evidence for the heritability of many psychiatric disorders. But such research depends on the validity of the EEA – the “equal environments assumption” – as an underlying premise. In this paper, several empirical studies which support the EEA are critically reviewed in terms of methodology and the way data has been processed in a mathematical model called “path analysis”. It turns out that studies investigating the EEA appear to be largely inadequate in terms of technique, as well as biased in the inferences drawn. Further, the “heritability” estimate – often taken to mean the influence of trait – specific genes – is merely a statistical abstraction derived from a matrix of correlations; this estimate encompasses many buried environmental effects so that “heritability” does not correspond to any underlying DNA structure. In conclusion, many MZ-DZ pedigree studies have dubious scientific value, given the non-viable premise of the EEA, as well as the misleading operational definition of what has been called “heritability”.

Revisiting MMORPGs in Support of Learning

2019 ◽  
pp. 187-214
Author(s):  
Bodi Anderson
Keyword(s):  
Empirical Studies ◽  
Role Playing ◽  
Operational Definition ◽  
Future Research ◽  
Educational Benefits ◽  
Role Playing Games ◽  
Player Game ◽  
Recent Trends ◽  
Definition Of ◽  
Education Psychology

This enhanced chapter revisits a previous literature analysis of research on the potential educational benefits of the use of massive multiplayer online role playing games (MMORPG) by considering both changes in the medium itself and recent trends in research. Initially, a working operational definition of MMORPGs in education is considered in light of research to date with a focus on how MMORPGs differ from most video games in terms of types of player-game interaction, levels of player-player interaction, and environments in which interaction occurs. Next considering previous and current theoretical and empirical studies on MMORPGs from a variety of disciplines, including education, psychology, and linguistics, a conceptual framework for the use of MMORPGs in support of learning is created. Finally, an overview of current research trends in MMORPGs is provided, concluding with suggestions concerning future research of the use of MMORPGs in support of learning.

scholarly journals Attributes of Effective Lecturing in the College Classroom

1993 ◽  
Vol 23 (2) ◽  
pp. 1-18
Author(s):  
Dieter J. Schonwetter
Keyword(s):  
Student Learning ◽  
Cognitive Processing ◽  
Empirical Studies ◽  
Operational Definition ◽  
Research Literature ◽  
College Classroom ◽  
Major Research ◽  
Critical Issues ◽  
Research Findings ◽  
Definition Of

The following paper highlights research on effective lecturing in the college classroom. First, critical issues concerning the operational definition of effective lecturing and the measurement criteria used to denote it are addressed. Next, major research findings are reported, beginning with correlational information reported by descriptive studies and ending with causal findings demonstrated by empirical studies. Current research literature identifies the following lecture attributes as important for student learning: expressiveness, clarity, and organization. These dimensions are defined by low-inference behaviours and supported by empirical studies. Furthermore, links between lecture attributes and certain student cognitive processing activities, explaining the facilitative qualities of effective lecturing on student learning, are hypothesized. Finally, implications for both practitioners and researchers are discussed.

scholarly journals Twin Studies, Molecular Genetics, Politics, and Tolerance: A Response to Beckwith and Morris

2008 ◽  
Vol 6 (4) ◽  
pp. 793-797 ◽  
Author(s):  
John R. Alford ◽  
Carolyn L. Funk ◽  
John R. Hibbing
Keyword(s):  
Molecular Genetics ◽  
Human Behavior ◽  
Behavioral Genetics ◽  
Twin Studies ◽  
Quarter Century ◽  
Political Orientations ◽  
Equal Environments Assumption ◽  
And Control ◽  
Equal Environments

Beckwith and Morris raise concerns about the value of twin studies for understanding the role of genetics in complex human behavior, but virtually all of their concerns have been raised and rebutted before. When it comes to the equal environments assumption (EEA), the best approach is to test for and control possible violations of the EEA on heritability estimates rather than merely rejecting all empirical evidence because of the possibility of EEA violations. In many respects, since the study of the genetic basis of complex human behaviors now includes many methods in addition to twin studies, Beckwith and Morris's critique applies more to the behavioral genetics of a quarter century ago than to today's multifaceted behavioral genetics. Twin studies establish that there is a sizeable genetic component to political orientations, thereby giving cause to look further at the nature of that role by using other methodologies, including molecular genetics. We conclude by pointing out that the normative implications of the relevance of genes to human behavior are not nearly as worrisome as Beckwith and Morris seem to believe.

DEFINING LISTED FAMILY CONTROLLED CORPORATIONS — AN AGENCY THEORY PERSPECTIVE

2010 ◽  
Vol 18 (04) ◽  
pp. 377-397 ◽  
Author(s):  
JAMES LAU
Keyword(s):  
Decision Making ◽  
Agency Theory ◽  
Family Firms ◽  
Empirical Studies ◽  
Significant Proportion ◽  
Operational Definition ◽  
Management Control ◽  
Family Needs ◽  
Decision Making Processes ◽  
Definition Of

Recent research shows that a significant proportion of listed corporations in a number of major financial markets across the world are classified as family firms. That classification is based on a number of different definitions of a family firm, using criteria such as an ownership threshold and/or the presence of a family member on the board of directors and/or in the top managerial positions. The lack of a universal definition of listed family controlled corporations may undermine the comparability or even the validity of any empirical results reported. This paper aims to resolve the diversity of definitions in use by developing an operational definition of listed family controlled corporations that is consistent with agency theory — the most commonly adopted theoretical framework in existing empirical studies. Based on agency theory, I argue that the key difference between family and non-family firms lies in the control of the decision making processes of the corporation. I further argue that a family needs to dominate the management control structure in order to control decision making processes.

Operationally defining family SMEs: a critical review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Paolo Roffia ◽  
Stefania Moracchiato ◽  
Eric Liguori ◽  
Sascha Kraus
Keyword(s):  
Family Business ◽  
Empirical Studies ◽  
Operational Definition ◽  
Three Dimensions ◽  
Content Type ◽  
Online Databases ◽  
Family Smes ◽  
Research Questions ◽  
And Performance ◽  
Definition Of

PurposeIn this study, we investigated the dilemma of devising an operational family business definition in the SME context. The existing family business literature mostly agrees with the validity of a theoretical model called F-PEC, which identifies family businesses by evaluating three dimensions: power, experience, and culture. Nonetheless, empirical studies on family SMEs still use just one or a few elements with many different thresholds to operationally define family SMEs, highlighting an unsolved definitional divergence among scholars, which limits the possibility of investigating the potential effects of family attributes on firms’ goals, structures, processes, and performance.Design/methodology/approachEmploying ancestry searching, online databases, and issue-by-issue searches from two decades (1990–2019), we analyzed 255 empirical studies that specified a family business’s operational definition (despite posing different research questions) and used a sample of small-sized and medium-sized enterprises (SMEs).FindingsResults showed ownership and governance/management are the most used elements in the operational definitions provided in the literature to date, but that there still is not a universally adopted operational definition of family SMEs in use today.Originality/valueThis paper is one of the first to comprehensively analyze and review the operationalized use of family SME definitions in the literature.

Sociopolitical Attitudes Through the Lens of Behavioral Genetics: Contributions from Dr Nicholas Martin

2020 ◽  
Vol 23 (2) ◽  
pp. 125-126
Author(s):  
Brad Verhulst
Keyword(s):  
Political Attitudes ◽  
Behavioral Genetics ◽  
Psychological Variables ◽  
Substantial Impact ◽  
Twin Model ◽  
Socially Constructed ◽  
Equal Environments Assumption ◽  
Sources Of Variation ◽  
Equal Environments ◽  
Typical Mode

AbstractProfessor Nicholas (Nick) Martin spearheaded initial investigations into the genetic basis of political attitudes and behaviors, demonstrating that behaviors that are perceived as socially constructed could have a biological basis. As he showed, the typical mode of inheritance for political attitudes consists of approximately equal proportions of variance from additive genetic, shared environmental and unique environmental sources. This differs from other psychological variables, such as personality traits, which tend to be characterized by genetic and unique environmental sources of variation. By treating political attitudes as a model phenotype, Nick Martin was able to leverage the unique pattern of observed intergenerational transmission for political attitudes to reexamine the quintessential assumptions of the classical twin model. Specifically, by creatively leveraging the nuances of the genetic architecture of political attitudes, he was able to demonstrate the robustness of the equal environments assumption and suggest corrections to account for assortative mating. These advances have had a substantial impact on both the fields of political science, as well as behavioral and quantitative genetics.

Copreneurs: An Exploration and Comparison to Other Family Businesses

2002 ◽  
Vol 15 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Margaret A. Fitzgerald ◽  
Glenn Muske
Keyword(s):  
Family Business ◽  
Empirical Studies ◽  
Operational Definition ◽  
Financial Success ◽  
Way Of Life ◽  
Several Variables ◽  
Home Based ◽  
National Family ◽  
Definition Of ◽  
Business Study

This paper reviews the definition of copreneurial couples used in empirical studies and addresses the difficulties associated with identifying these couples in research studies. Then, using an operational definition of copreneurs and data from the 1997 National Family Business Study (NFBS), copreneurs and noncopreneurs are compared on general demographic and business-related variables, lifestyle indicators, and measures of financial success. Descriptive findings indicate that copreneurs differ significantly from noncopreneurs on several variables. On average, copreneurial households are more likely to live in a rural area, have spouses working more weeks per year in the business, and have home-based businesses than are noncopreneurial households. Copreneurs report significantly lower levels on all objective and subjective measures of financial success than do noncopreneurs. They are more likely to view business as a way of life rather than a way to earn income when compared to noncopreneurs.

scholarly journals Defining Yoga-Nidra: Traditional Accounts, Physiological Research, and Future Directions

2013 ◽  
Vol 23 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Stephen Parker ◽  
Swami Veda Bharati ◽  
Manuel Fernandez
Keyword(s):  
Guided Imagery ◽  
Empirical Studies ◽  
Operational Definition ◽  
Future Research ◽  
Future Directions ◽  
Definition Of ◽  
Yoga Nidra ◽  
Physiological Research

The term yoga-nidra has been used in many empirical studies to refer to relaxation and guided imagery. These techniques do not represent the intention or physiological correlates of yoganidra discussed in the traditional yoga literature. We propose an operational definition of yoga-nidra that is supported by several physiologically testable hypotheses regarding its outcomes and effects. Traditional descriptions of yoga-nidra and contemporary accounts of its practice are reviewed, and studies examining the physiological correlates of yoga-nidra are examined. Proposed hypotheses for future research using this operational definition are provided.

Understanding functional illiteracy from a policy, adult education, and cognition point of view: Towards a joint referent framework

2019 ◽  
Vol 30 (2) ◽  
pp. 109-122
Author(s):  
Aleksandar Bulajić ◽  
Miomir Despotović ◽  
Thomas Lachmann
Keyword(s):  
Adult Education ◽  
Operational Definition ◽  
Literacy Skills ◽  
Point Of View ◽  
Industrialized Countries ◽  
Functional Illiteracy ◽  
Scale Levels ◽  
Components Of Reading ◽  
The One ◽  
Definition Of

Abstract. The article discusses the emergence of a functional literacy construct and the rediscovery of illiteracy in industrialized countries during the second half of the 20th century. It offers a short explanation of how the construct evolved over time. In addition, it explores how functional (il)literacy is conceived differently by research discourses of cognitive and neural studies, on the one hand, and by prescriptive and normative international policy documents and adult education, on the other hand. Furthermore, it analyses how literacy skills surveys such as the Level One Study (leo.) or the PIAAC may help to bridge the gap between cognitive and more practical and educational approaches to literacy, the goal being to place the functional illiteracy (FI) construct within its existing scale levels. It also sheds more light on the way in which FI can be perceived in terms of different cognitive processes and underlying components of reading. By building on the previous work of other authors and previous definitions, the article brings together different views of FI and offers a perspective for a needed operational definition of the concept, which would be an appropriate reference point for future educational, political, and scientific utilization.

“The Unconscious” in Current Psychology

2010 ◽  
Vol 15 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Elisabeth Norman
Keyword(s):  
Cognitive Psychology ◽  
Verbal Report ◽  
Psychological Research ◽  
Operational Definition ◽  
The Unconscious ◽  
Apparent Lack ◽  
Unconscious Processing ◽  
Unconscious Processes ◽  
Intermediate States ◽  
Definition Of

A series of vignette examples taken from psychological research on motivation, emotion, decision making, and attitudes illustrates how the influence of unconscious processes is often measured in a range of different behaviors. However, the selected studies share an apparent lack of explicit operational definition of what is meant by consciousness, and there seems to be substantial disagreement about the properties of conscious versus unconscious processing: Consciousness is sometimes equated with attention, sometimes with verbal report ability, and sometimes operationalized in terms of behavioral dissociations between different performance measures. Moreover, the examples all seem to share a dichotomous view of conscious and unconscious processes as being qualitatively different. It is suggested that cognitive research on consciousness can help resolve the apparent disagreement about how to define and measure unconscious processing, as is illustrated by a selection of operational definitions and empirical findings from modern cognitive psychology. These empirical findings also point to the existence of intermediate states of conscious awareness, not easily classifiable as either purely conscious or purely unconscious. Recent hypotheses from cognitive psychology, supplemented with models from social, developmental, and clinical psychology, are then presented all of which are compatible with the view of consciousness as a graded rather than an all-or-none phenomenon. Such a view of consciousness would open up for explorations of intermediate states of awareness in addition to more purely conscious or purely unconscious states and thereby increase our understanding of the seemingly “unconscious” aspects of mental life.

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