16,449 research outputs found
Lab Experiments are a Major Source of Knowledge in the Social Sciences
Laboratory experiments are a widely used methodology for advancing causal knowledge in the physical and life sciences. With the exception of psychology, the adoption of laboratory experiments has been much slower in the social sciences, although during the last two decades, the use of lab experiments has accelerated. Nonetheless, there remains considerable resistance among social scientists who argue that lab experiments lack ârealismâ and âgeneralizabilityâ. In this article we discuss the advantages and limitations of laboratory social science experiments by comparing them to research based on non-experimental data and to field experiments. We argue that many recent objections against lab experiments are misguided and that even more lab experiments should be conducted.laboratory experiments, field experiments, controlled variation
Lab Experiments are a Major Source of Knowledge in the Social Sciences
Laboratory experiments are a widely used methodology for advancing causal knowledge in the physical and life sciences. With the exception of psychology, the adoption of laboratory experiments has been much slower in the social sciences, although during the last two decades, the use of lab experiments has accelerated. Nonetheless, there remains considerable resistance among social scientists who argue that lab experiments lack ârealismâ and âgeneralizabilityâ. In this article we discuss the advantages and limitations of laboratory social science experiments by comparing them to research based on non-experimental data and to field experiments. We argue that many recent objections against lab experiments are misguided and that even more lab experiments should be conducted.laboratory experiments, field experiments, controlled variation
Lab Experiments Are a Major Source of Knowledge in the Social Sciences
Laboratory experiments are a widely used methodology for advancing causal knowledge in the physical and life sciences. With the exception of psychology, the adoption of laboratory experiments has been much slower in the social sciences, although during the last two decades, the use of lab experiments has accelerated. Nonetheless, there remains considerable resistance among social scientists who argue that lab experiments lack "realism" and "generalizability". In this article we discuss the advantages and limitations of laboratory social science experiments by comparing them to research based on non-experimental data and to field experiments. We argue that many recent objections against lab experiments are misguided and that even more lab experiments should be conducted.laboratory experiments, field experiments, controlled variation
Asymptotic Conditional Distribution of Exceedance Counts: Fragility Index with Different Margins
Let be a random vector, whose components are not
necessarily independent nor are they required to have identical distribution
functions . Denote by the number of exceedances among
above a high threshold . The fragility index, defined by
if this limit exists, measures the
asymptotic stability of the stochastic system as the threshold
increases. The system is called stable if and fragile otherwise. In this
paper we show that the asymptotic conditional distribution of exceedance counts
(ACDEC) , , exists, if the
copula of is in the domain of attraction of a multivariate extreme
value distribution, and if
exists for
and some . This enables the computation of
the FI corresponding to and of the extended FI as well as of the
asymptotic distribution of the exceedance cluster length also in that case,
where the components of are not identically distributed
Strain localization in a shear transformation zone model for amorphous solids
We model a sheared disordered solid using the theory of Shear Transformation
Zones (STZs). In this mean-field continuum model the density of zones is
governed by an effective temperature that approaches a steady state value as
energy is dissipated. We compare the STZ model to simulations by Shi, et
al.(Phys. Rev. Lett. 98 185505 2007), finding that the model generates
solutions that fit the data,exhibit strain localization, and capture important
features of the localization process. We show that perturbations to the
effective temperature grow due to an instability in the transient dynamics, but
unstable systems do not always develop shear bands. Nonlinear energy
dissipation processes interact with perturbation growth to determine whether a
material exhibits strain localization. By estimating the effects of these
interactions, we derive a criterion that determines which materials exhibit
shear bands based on the initial conditions alone. We also show that the shear
band width is not set by an inherent diffusion length scale but instead by a
dynamical scale that depends on the imposed strain rate.Comment: 8 figures, references added, typos correcte
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