249 research outputs found
How to Educate Entrepreneurs?
Entrepreneurship education has two purposes: To improve students’ entrepreneurial skills and to provide impetus to those suited to entrepreneurship while discouraging the rest. While entrepreneurship education helps students to make a vocational decision its effects may conflict for those not suited to entrepreneurship. This study shows that vocational and the skill formation effects of entrepreneurship education can be identified empirically by drawing on the Theory of Planned Behavior. This is embedded in a structural equation model which we estimate and test using a robust 2SLS estimator. We find that the attitudinal factors posited by the Theory of Planned Behavior are positively correlated with students’ entrepreneurial intentions. While conflicting effects of vocational and skill directed course content are observed in some individuals, overall these types of content are complements. This finding contradicts previous results in the literature. We reconcile the conflicting findings and discuss implications for the design of entrepreneurship courses
Extrapolation for Time-Series and Cross-Sectional Data
Extrapolation methods are reliable, objective, inexpensive, quick, and easily automated. As a result, they are widely used, especially for inventory and production forecasts, for operational planning for up to two years ahead, and for long-term forecasts in some situations, such as population forecasting. This paper provides principles for selecting and preparing data, making seasonal adjustments, extrapolating, assessing uncertainty, and identifying when to use extrapolation. The principles are based on received wisdom (i.e., experts’ commonly held opinions) and on empirical studies. Some of the more important principles are:• In selecting and preparing data, use all relevant data and adjust the data for important events that occurred in the past.• Make seasonal adjustments only when seasonal effects are expected and only if there is good evidence by which to measure them.• In extrapolating, use simple functional forms. Weight the most recent data heavily if there are small measurement errors, stable series, and short forecast horizons. Domain knowledge and forecasting expertise can help to select effective extrapolation procedures. When there is uncertainty, be conservative in forecasting trends. Update extrapolation models as new data are received.• To assess uncertainty, make empirical estimates to establish prediction intervals.• Use pure extrapolation when many forecasts are required, little is known about the situation, the situation is stable, and expert forecasts might be biased
Individual biases, cultural evolution, and the statistical nature of language universals: the case of colour naming systems
Language universals have long been attributed to an innate Universal Grammar. An alternative explanation states that linguistic universals emerged independently in every language in response to shared cognitive or perceptual biases. A computational model has recently shown how this could be the case, focusing on the paradigmatic example of the universal properties of colour naming patterns, and producing results in quantitative agreement with the experimental data. Here we investigate the role of an individual perceptual bias in the framework of the model. We study how, and to what extent, the structure of the bias influences the corresponding linguistic universal patterns. We show that the cultural history of a group of speakers introduces population-specific constraints that act against the pressure for uniformity arising from the individual bias, and we clarify the interplay between these two forces
Search for R-parity violating supersymmetry via the LLE couplings lambda_{121}, lambda_{122} or lambda_{133} in ppbar collisions at sqrt(s)=1.96 TeV
A search for gaugino pair production with a trilepton signature in the
framework of R-parity violating supersymmetry via the couplings lambda_121,
lambda_122, or lambda_133 is presented. The data, corresponding to an
integrated luminosity of L~360/pb, were collected from April 2002 to August
2004 with the D0 detector at the Fermilab Tevatron Collider, at a
center-of-mass energy of sqrt(s)=1.96 TeV. This analysis considers final states
with three charged leptons with the flavor combinations eel, mumul, and eetau
(l=e or mu). No evidence for supersymmetry is found and limits at the 95%
confidence level are set on the gaugino pair production cross section and lower
bounds on the masses of the lightest neutralino and chargino are derived in two
supersymmetric models.Comment: 9 pages, 4 figures (fig2 includes 3 subfigures
Search for Neutral Higgs Bosons Decaying to Tau Pairs in p-pbar Collisions at sqrt(s) = 1.96 TeV
A search for the production of neutral Higgs bosons Phi decaying into
tau^+tau^- final states in p-pbar collisions at a center-of-mass energy of 1.96
TeV is presented. The data, corresponding to an integrated luminosity of up to
348 pb^-1, were collected by the D0 experiment at the Fermilab Tevatron
Collider. Since no excess compared to the expectation from standard model
processes is found, limits on the production cross section times branching
ratio are set. The results are combined with those obtained from the D0 search
for Phi b(b) to b-bbar-b(bbar) and are interpreted in the minimal
supersymmetric standard model.Comment: Version accpeted by Phys. Rev. Lett. (minor changes
Search for W' boson production in the W'->tb decay channel
We present a search for the production of a new heavy gauge boson W' that
decays to a top quark and a bottom quark. We have analyzed 230 pb^{-1} of data
collected with the Dzero detector at the Fermilab Tevatron collider at a
center-of-mass energy of 1.96 TeV. No significant excess of events above the
standard model expectation is found in any region of the final state invariant
mass distribution. We set upper limits on the production cross section of W'
bosons times branching ratio to top quarks at the 95% confidence level for
several different W' boson masses. We exclude masses between 200 GeV and 610
GeV for a W' boson with standard-model-like couplings, between 200 GeV and 630
GeV for a W' boson with right-handed couplings that is allowed to decay to both
leptons and quarks, and between 200 GeV and 670 GeV for a W' boson with
right-handed couplings that is only allowed to decay to quarks.Comment: 9 pages, 6 figures, accepted by Phys. Lett.
Measurement of the Lifetime Using Semileptonic Decays
We report a measurement of the lifetime in the semileptonic decay
channel (and its charge conjugate), using
approximately 0.4 fb of data collected with the D0 detector during 2002
-- 2004. We have reconstructed 5176 signal events, where the
is identified via the decay , followed by . Using these events, we have measured the lifetime to be
. This is the most precise measurement of the lifetime to date.Comment: To appear in Phys. Rev. Lett., 7 pages, 2 figure
Search for the Rare Decay B0_s -> phi mu^+ mu- with the D0 Detector
We present a search for the flavor-changing neutral current decay B0_s -> phi
mu+ mu- using about 0.45 fb^-1 of data collected in p \bar p collisions at
sqrt{s} =1.96 TeV with the D{\O}detector at the Fermilab Tevatron Collider. We
find an upper limit on the branching ratio of this decay normalized to B0_s ->
J/psi phi of B(B0_s -> phi mu+ mu-)/B(B0_s -> J/psi phi) < 4.4\times 10^{-3} at
the 95% C.L. Using the central value of the world average branching fraction of
B0_s -> J/psi phi, the limit corresponds to B(B0_s -> phi mu+ mu-) < 4.1 \times
10^{-6} at the 95% C.L., the most stringent upper bound to date.Comment: 7 pages, 2 figures, LaTeX, to be submitted to Physical Review Letter
Search for a heavy resonance decaying into a Z+jet final state in p-pbar collisions at sqrt(s) = 1.96 TeV using the D0 detector
We have searched for a heavy resonance decaying into a Z+jet final state in
p-pbar collisions at a center of mass energy of 1.96 TeV at the Fermilab
Tevatron collider using the D0 detector. No indication for such a resonance was
found in a data sample corresponding to an integrated luminosity of 370/pb. We
set upper limits on the cross section times branching fraction for heavy
resonance production at the 95% C.L. as a function of the resonance mass and
width. The limits are interpreted within the framework of a specific model of
excited quark production.Comment: 8 pages, 5 figures, submitted to Physical Review
Multivariate searches for single top quark production with the D0 detector
We present a search for electroweak production of single top quarks in the
s-channel (p-pbar -> t bbar + X) and t-channel (p-pbar -> tq bbar + X) modes.
We have analyzed 230 pb^(-1) of data collected with the D0 detector at the
Fermilab Tevatron collider at a center-of-mass energy of sqrt(s) = 1.96 TeV.
Two separate analysis methods are used: neural networks and a cut-based
analysis. No evidence for a single top quark signal is found. We set 95%
confidence level upper limits on the production cross sections using Bayesian
statistics, based on event counts and binned likelihoods formed from the neural
network output. The limits from the neural network (cut-based) analysis are 6.4
pb (10.6 pb) in the s-channel and 5.0 pb (11.3 pb) in the t-channel.Comment: submitted to Phys. Rev. D, Fermilab preprint Fermilab-Pub-06/069-
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