Showing papers by "Roy Thurik published in 2017"

Meta-GWAS Accuracy and Power (MetaGAP) Calculator Shows that Hiding Heritability Is Partially Due to Imperfect Genetic Correlations across Studies

Abstract: Large-scale genome-wide association results are typically obtained from a fixed-effects meta-analysis of GWAS summary statistics from multiple studies spanning different regions and/or time periods. This approach averages the estimated effects of genetic variants across studies. In case genetic effects are heterogeneous across studies, the statistical power of a GWAS and the predictive accuracy of polygenic scores are attenuated, contributing to the so-called 'missing heritability'. Here, we describe the online Meta-GWAS Accuracy and Power (MetaGAP) calculator (available at www.devlaming.eu) which quantifies this attenuation based on a novel multi-study framework. By means of simulation studies, we show that under a wide range of genetic architectures, the statistical power and predictive accuracy provided by this calculator are accurate. We compare the predictions from the MetaGAP calculator with actual results obtained in the GWAS literature. Specifically, we use genomic-relatedness-matrix restricted maximum likelihood to estimate the SNP heritability and cross-study genetic correlation of height, BMI, years of education, and self-rated health in three large samples. These estimates are used as input parameters for the MetaGAP calculator. Results from the calculator suggest that cross-study heterogeneity has led to attenuation of statistical power and predictive accuracy in recent large-scale GWAS efforts on these traits (e.g., for years of education, we estimate a relative loss of 51-62% in the number of genome-wide significant loci and a relative loss in polygenic score R2 of 36-38%). Hence, cross-study heterogeneity contributes to the missing heritability.

Time pressure and team member creativity within R&D projects: The role of learning orientation and knowledge sourcing

Abstract: This paper examines team member creativity within RD and (2) a negative effect moderating the relationship between team member knowledge sourcing and creativity, where high levels of time pressure act as a constraint of cognitive processes (i.e., constraining effect). Findings show that learning orientation and knowledge sourcing behaviors play a central role in reducing team members' experience of time pressure and in fostering their creativity. There are important theoretical and practical implications relating to how team leaders may manage knowledge sourcing and time pressure within R&D projects to enhance team member creativity.

A note on the use of Egger regression in Mendelian randomization studies.

Abstract: A large number of epidemiological studies use genetic variants as instrumental variables to infer causal relationships. For a genetic variant to be a valid instrument in these so-called Mendelian randomization (MR) studies, three assumptions need to hold: __(i)__ the genetic variant is associated with the exposure of interest (relevance assumption); __(ii)__ the genetic variants should be independent of all confounders (independence assumption); __(iii)__ the genetic variants only effect the outcome through the exposure of interest (exclusion restriction). Without specific knowledge about the biological mechanisms affected by genetic variants, it is virtually impossible to prove that the exclusion restriction holds for a specific genetic variant. For example, genetic variants may have pleiotropic effects on both the exposure and the outcome through different biological pathways. [...]

Mode of Entry into Hybrid Entrepreneurship: New Venture Start-Up Versus Business Takeover

Abstract: Many entrepreneurs start their ventures while retaining jobs in wage employment; this phenomenon is called hybrid entrepreneurship. Little is known about the entry modes (new venture start-up vs. business takeover) of hybrid entrepreneurs. Our study aims to close this gap by investigating the path to hybrid entrepreneurship. Using a large sample of French hybrid entrepreneurs, we show that educational attainment and management experience are associated with new venture start-up, whereas being female, having worker experience, and having received social benefits are linked to business takeover. With these results, our study contributes to research on hybrid entrepreneurship and entrepreneurship entry modes. Moreover, it informs policy makers about the nature of hybrid entrepreneurship and contributes to the design of effective policies to promote business takeover, which is of high interest, given the growing number of businesses seeking outside successors

Mental Health and Entrepreneurial Exit

Abstract: The positive and glamorous Schumpeterian role that entrepreneurs play in the macro-economy spilled over to the field of psychology, where mainly positive personality traits, such as self-efficacy, ...

Mode of Entry into Hybrid Entrepreneurship: New Venture Start-Up versus Business Takeover

Abstract: Many entrepreneurs start their ventures while retaining jobs in wage employment; this phenomenon is called hybrid entrepreneurship. Little is known about the entry modes (new venture start-up vs. business takeover) of hybrid entrepreneurs. Our study aims to close this gap by investigating the path to hybrid entrepreneurship. Using a large sample of French hybrid entrepreneurs, we show that educational attainment and management experience are associated with new venture start-up, whereas being female, having worker experience, and having received social benefits are linked to business takeover. With these results, our study contributes to research on hybrid entrepreneurship and entrepreneurship entry modes. Moreover, it informs policy makers about the nature of hybrid entrepreneurship and contributes to the design of effective policies to promote business takeover, which is of high interest, given the growing number of businesses seeking outside successors.

Entrepreneurship & Attention Deficit/Hyperactivity Disorder: A Large-Scale Study Involving the Clinical Condition of Adhd

Abstract: A growing conversation has emerged linking ostensibly dark or pathological individual-level characteristics to entrepreneurship. Attention Deficit/Hyperactivity Disorder (ADHD) emerged as a proof-of-concept phenomenon. Recent studies in entrepreneurship journals have made great strides – articulating the theoretical relevance of ADHD-type behavior in entrepreneurship, and suggesting a positive link consistent with narratives in the popular press. While the recent research has made important inroads, quantitative studies have yet to empirically examine ADHD in line with its theoretical roots and definition – as a full-blown clinical disorder. The present paper contributes by providing a theoretically-empirically aligned test of the connection between clinical ADHD and entrepreneurial intention as well as action.