705 research outputs found
Returns to Private Education in Peru
The private provision of educational services has been representing an increasing fraction of the Peruvian schooling system, especially in recentdecades. While there have been many claims about the differences in quality between private and public schools, there is no complete assessment of the different impacts of these two type of providers on the labor markets. This paper attempts to provide such a comprehensive overview by exploring private-public differences in the individual returns to education in Urban Peru. Exploiting a rich pair of data sets (ENNIV 1997 and 2000) that include questions on type of education (public vs. private) for each educational level (primary, secondary, technical tertiary and university tertiary) to a representative sample of adults, this paper measures the differences in labor earnings for all possible educational trajectories. The results indicate higher returns to education for those who attended private schools than those who attended the public system. Nonetheless, these higher returns also show higher dispersion, reflecting wider quality heterogeneity within the private system. The private-public differences in returns are more pronounced at the secondary than at any other educational level. On the other hand, the private-public differences in returns from technical education are almost nonexistent. A cohort approach paired with a rolling-windows technique allows us to capture generational evolutions of the private-public differences. The results indicate that these differences have been increasing during the last two decades.
Optimal Bandwidth Choice for Robust Bias Corrected Inference in Regression Discontinuity Designs
Modern empirical work in Regression Discontinuity (RD) designs often employs
local polynomial estimation and inference with a mean square error (MSE)
optimal bandwidth choice. This bandwidth yields an MSE-optimal RD treatment
effect estimator, but is by construction invalid for inference. Robust bias
corrected (RBC) inference methods are valid when using the MSE-optimal
bandwidth, but we show they yield suboptimal confidence intervals in terms of
coverage error. We establish valid coverage error expansions for RBC confidence
interval estimators and use these results to propose new inference-optimal
bandwidth choices for forming these intervals. We find that the standard
MSE-optimal bandwidth for the RD point estimator is too large when the goal is
to construct RBC confidence intervals with the smallest coverage error. We
further optimize the constant terms behind the coverage error to derive new
optimal choices for the auxiliary bandwidth required for RBC inference. Our
expansions also establish that RBC inference yields higher-order refinements
(relative to traditional undersmoothing) in the context of RD designs. Our main
results cover sharp and sharp kink RD designs under conditional
heteroskedasticity, and we discuss extensions to fuzzy and other RD designs,
clustered sampling, and pre-intervention covariates adjustments. The
theoretical findings are illustrated with a Monte Carlo experiment and an
empirical application, and the main methodological results are available in
\texttt{R} and \texttt{Stata} packages
Recommended from our members
Globule leukocytes and mast cells in the rat trachea: their number, distribution, and response to compound 48/80 and dexamethasone.
Globule leukocytes in the epithelium of the rat trachea may be counterparts of mucosal mast cells that are located in the gastrointestinal tract. If they are indeed similar to mucosal mast cells, globule leukocytes would be expected to decrease in number in rats treated with dexamethasone but not in rats treated with compound 48/80, an agent which causes non-antigenic degranulation of connective tissue mast cells. In this study, we determined the number and compared the distribution of globule leukocytes and connective tissue mast cells in the tracheas of pathogen-free rats. We then determined whether the number of these two types of cells changes in rats treated for 5 days with compound 48/80, dexamethasone, a combination of compound 48/80 and dexamethasone, or saline. We identified globule leukocytes and mast cells in whole mounts and histological sections of rat tracheas by using a histochemical reaction that demonstrates the chymotrypsin-like protease (chloroacetate esterase) present in mast cell granules. Using this method, we found that approximately 225,000 globule leukocytes were present in the epithelium of the trachea. These cells were most abundant in the rostral trachea. Rats treated with dexamethasone had a 91% reduction in the number of globule leukocytes with protease-containing granules, but rats treated with compound 48/80 had a normal number of these cells. We found some 55,000 connective tissue mast cells in the same tracheas. Mast cells were most abundant in the posterior membrane of the caudal trachea and in the lamina propria between cartilaginous rings. Rats treated with compound 48/80 had a 96% reduction in mast cells with protease-containing granules, but rats treated with dexamethasone had a normal complement of mast cells. We conclude that globule leukocytes are abundant in the tracheas of healthy rats, are similar in morphology and pharmacological responses to mucosal mast cells located in other organs of rats, and are more numerous than and have a different distribution than connective tissue mast cells. Globule leukocytes in the tracheal epithelium may have a role in respiratory defenses similar to that of mucosal mast cells in other organs
Bayesian inference of a negative quantity from positive measurement results
In this paper the Bayesian analysis is applied to assign a probability
density to the value of a quantity having a definite sign. This analysis is
logically consistent with the results, positive or negative, of repeated
measurements. Results are used to estimate the atom density shift in a caesium
fountain clock. The comparison with the classical statistical analysis is also
reported and the advantages of the Bayesian approach for the realization of the
time unit are discussed.Comment: 10 pages, 4 figures, submitted to Metrologi
On the Effect of Bias Estimation on Coverage Accuracy in Nonparametric Inference
Nonparametric methods play a central role in modern empirical work. While
they provide inference procedures that are more robust to parametric
misspecification bias, they may be quite sensitive to tuning parameter choices.
We study the effects of bias correction on confidence interval coverage in the
context of kernel density and local polynomial regression estimation, and prove
that bias correction can be preferred to undersmoothing for minimizing coverage
error and increasing robustness to tuning parameter choice. This is achieved
using a novel, yet simple, Studentization, which leads to a new way of
constructing kernel-based bias-corrected confidence intervals. In addition, for
practical cases, we derive coverage error optimal bandwidths and discuss
easy-to-implement bandwidth selectors. For interior points, we show that the
MSE-optimal bandwidth for the original point estimator (before bias correction)
delivers the fastest coverage error decay rate after bias correction when
second-order (equivalent) kernels are employed, but is otherwise suboptimal
because it is too "large". Finally, for odd-degree local polynomial regression,
we show that, as with point estimation, coverage error adapts to boundary
points automatically when appropriate Studentization is used; however, the
MSE-optimal bandwidth for the original point estimator is suboptimal. All the
results are established using valid Edgeworth expansions and illustrated with
simulated data. Our findings have important consequences for empirical work as
they indicate that bias-corrected confidence intervals, coupled with
appropriate standard errors, have smaller coverage error and are less sensitive
to tuning parameter choices in practically relevant cases where additional
smoothness is available
Regression Discontinuity Designs Using Covariates
We study regression discontinuity designs when covariates are included in the
estimation. We examine local polynomial estimators that include discrete or
continuous covariates in an additive separable way, but without imposing any
parametric restrictions on the underlying population regression functions. We
recommend a covariate-adjustment approach that retains consistency under
intuitive conditions, and characterize the potential for estimation and
inference improvements. We also present new covariate-adjusted mean squared
error expansions and robust bias-corrected inference procedures, with
heteroskedasticity-consistent and cluster-robust standard errors. An empirical
illustration and an extensive simulation study is presented. All methods are
implemented in \texttt{R} and \texttt{Stata} software packages
Competitive jazz festivals: what motivates Northern California instrumental music teachers to participate in them?
In this study, I explored the motivations of high school instrumental music teachers to participate in competitive jazz festivals, specifically those sponsored by the California Music Educators Association (CMEA) Bay Section. I was interested in learning the specific needs participation in competitive festivals satisfied for high school music educators. Based on the tenets of Self-Determination Theory (SDT), I investigated whether the three basic psychological needs of autonomy, competency, and relatedness were among the needs being satisfied. I was curious whether an individual’s background in jazz or any other factors had any bearing on their decision to participate. Through interviews teachers shared their experiences, both positive and negative, of participating in competitive jazz festivals.
The following research questions guided this study:
1. What motivates high school music teachers to participate in competitive jazz
festivals?
2. What specific needs are satisfied through their participation?
3. How does one’s jazz background influence motivation to participate in CMEA Bay Section events?
In answering the aforementioned research questions, I chose a case study design. Interviews with twenty-nine high school instrumental music teachers were conducted at their respective work sites, except for three phone interviews and one via electronic mail.
Five themes identified through data analysis about festivals specifically included feelings about competition, judging, negative feedback from adjudicators, hearing and seeing other groups, and a suggestion for the addition of a clinic for all participating groups. Six general themes about CMEA Bay Section or participants’ feelings included more progressive thinking, a perception that youth among adjudicators was inadequately represented, a notion that festivals provided opportunities for process and growth, a feeling that many were forced to weigh the costs versus the benefits of participation, an expressed feeling of isolation in the profession, and a lack of awareness on the part of administrators about their participation in CMEA Bay Section jazz festivals
Realization of a twin beam source based on four-wave mixing in Cesium
Four-wave mixing (4WM) is a known source of intense non-classical twin beams.
It can be generated when an intense laser beam (the pump) and a weak laser beam
(the seed) overlap in a medium (here cesium vapor), with
frequencies close to resonance with atomic transitions. The twin beams
generated by 4WM have frequencies naturally close to atomic transitions, and
can be intense (gain ) even in the CW pump regime, which is not the case
for PDC phenomenon in non-linear crystals. So, 4WM is well suited
for atom-light interaction and atom-based quantum protocols. Here we present
the first realization of a source of 4-wave mixing exploiting line of
Cesium atoms.Comment: 10 pages, 10 figure
Distributed Raman optical amplification in phase coherent transfer of optical frequencies
We describe the application of Raman Optical-fiber Amplification (ROA) for
the phase coherent transfer of optical frequencies in an optical fiber link.
ROA uses the transmission fiber itself as a gain medium for bi-directional
coherent amplification. In a test setup we evaluated the ROA in terms of on-off
gain, signal-to-noise ratio, and phase noise added to the carrier. We
transferred a laser frequency in a 200 km optical fiber link with an additional
16 dB fixed attenuator (equivalent to 275 km of fiber on a single span), and
evaluated both co-propagating and counter-propagating amplification pump
schemes, demonstrating nonlinear effects limiting the co-propagating pump
configuration. The frequency at the remote end has a fractional frequency
instability of 3e-19 over 1000 s with the optical fiber link noise
compensation
- …