scholarly journals Treatment and Selection Effects of Formal Workplace Mentorship Programs

2021 ◽  
Author(s):  
Jason Sandvik ◽  
Richard Saouma ◽  
Nathan Seegert ◽  
Christopher Stanton
Keyword(s):  
Selection Effects ◽  
Mentorship Programs

Treatment and Selection Effects of Formal Workplace Mentorship Programs

2021 ◽  
Author(s):  
Jason Sandvik ◽  
Richard E. Saouma ◽  
Nathan Seegert ◽  
Christopher Stanton
Keyword(s):  
Selection Effects ◽  
Mentorship Programs

On the Mathematical Basis of Zelen’s Prerandomized Designs

1985 ◽  
Vol 24 (03) ◽  
pp. 120-130 ◽  
Author(s):  
E. Brunner ◽  
N. Neumann
Keyword(s):  
Clinical Trial ◽  
Normal Distribution ◽  
Random Variables ◽  
Small Samples ◽  
Selection Effects ◽  
Sample Sizes ◽  
Mathematical Basis ◽  
Additional Assumptions

SummaryThe mathematical basis of Zelen’s suggestion [4] of pre randomizing patients in a clinical trial and then asking them for their consent is investigated. The first problem is to estimate the therapy and selection effects. In the simple prerandomized design (PRD) this is possible without any problems. Similar observations have been made by Anbar [1] and McHugh [3]. However, for the double PRD additional assumptions are needed in order to render therapy and selection effects estimable. The second problem is to determine the distribution of the statistics. It has to be taken into consideration that the sample sizes are random variables in the PRDs. This is why the distribution of the statistics can only be determined asymptotically, even under the assumption of normal distribution. The behaviour of the statistics for small samples is investigated by means of simulations, where the statistics considered in the present paper are compared with the statistics suggested by Ihm [2]. It turns out that the statistics suggested in [2] may lead to anticonservative decisions, whereas the “canonical statistics” suggested by Zelen [4] and considered in the present paper keep the level quite well or may lead to slightly conservative decisions, if there are considerable selection effects.

Improving medical student recruitment to neurosurgery

2020 ◽  
Vol 133 (3) ◽  
pp. 848-854 ◽  
Author(s):  
Daniel Lubelski ◽  
Roy Xiao ◽  
Debraj Mukherjee ◽  
William W. Ashley ◽  
Timothy Witham ◽  
...  
Keyword(s):  
Medical Student ◽  
Medical Students ◽  
Interest Group ◽  
National Level ◽  
Program Directors ◽  
Student Recruitment ◽  
Research Opportunities ◽  
Research Activities ◽  
Lecture Series ◽  
Mentorship Programs

OBJECTIVENeurosurgery seeks to attract the best and brightest medical students; however, there is often a lack of early exposure to the field, among other possible barriers. The authors sought to identify successful practices that can be implemented to improve medical student recruitment to neurosurgery.METHODSUnited States neurosurgery residency program directors were surveyed to determine the number of medical student rotators and medical students matching into a neurosurgery residency from their programs between 2010 and 2016. Program directors were asked about the ways their respective institutions integrated medical students into departmental clinical and research activities.RESULTSComplete responses were received from 30/110 institutions. Fifty-two percent of the institutions had neurosurgery didactic lectures for 1st- and 2nd-year medical students (MS1/2), and 87% had didactics for MS3/4. Seventy-seven percent of departments had a neurosurgery interest group, which was the most common method used to integrate medical students into the department. Other forms of outreach included formal mentorship programs (53%), lecture series (57%), and neurosurgery anatomy labs (40%). Seventy-three percent of programs provided research opportunities to medical students, and 57% indicated that the schools had a formal research requirement. On average, 3 medical students did a rotation in each neurosurgery department and 1 matched into neurosurgery each year. However, there was substantial variability among programs. Over the 2010–2016 period, the responding institutions matched as many as 4% of the graduating class into neurosurgery per year, whereas others matched 0%–1%. Departments that matched a greater (≥ 1% per year) number of medical students into neurosurgery were significantly more likely to have a neurosurgery interest group and formal research requirements. A greater percentage of high-matching programs had neurosurgery mentorship programs, lecture series, and cadaver training opportunities compared to the other institutions.CONCLUSIONSIn recent decades, the number of applicants to neurosurgery has decreased. A major deterrent may be the delayed exposure of medical students to neurosurgery. Institutions with early preclinical exposure, active neurosurgery interest groups, research opportunities, and strong mentorship recruit and match more students into neurosurgery. Implementing such initiatives on a national level may increase the number of highly qualified medical students pursuing neurosurgery.

Qualified Immunity Selection Effects

2018 ◽  
Author(s):  
Joanna C. Schwartz
Keyword(s):  
Selection Effects

Shifts from complementarity to selection effects maintain high productivity in maize/legume intercropping systems

2021 ◽  
Author(s):  
Wei‐Ping Zhang ◽  
Sai‐Nan Gao ◽  
Zhao‐Xin Li ◽  
Hua‐Sen Xu ◽  
Hao Yang ◽  
...  
Keyword(s):  
Selection Effects ◽  
High Productivity

How effective are training and mentorship programs for entrepreneurs at promoting entrepreneurial activity? An impact evaluation

2021 ◽  
Vol 1 (7) ◽  
Author(s):  
Martin Pereyra ◽  
Diego Aboal ◽  
Flavia Rovira
Keyword(s):  
Impact Evaluation ◽  
Entrepreneurial Activity ◽  
Mentorship Programs

scholarly journals Does Emancipation Matter? Fertility of Chinese International Migrants to the United States and Nonmigrants during China’s One-child Policy Period

2021 ◽  
pp. 019791832199478
Author(s):  
Wanli Nie ◽  
Pau Baizan
Keyword(s):  
United States ◽  
International Migration ◽  
Chinese Women ◽  
The United States ◽  
Selection Effects ◽  
Birth Cohorts ◽  
Family Policies ◽  
Chinese Migrants ◽  
And Migration ◽  
The Impact

This article investigates the impact of international migration to the United States on the level and timing of Chinese migrants’ fertility. We compare Chinese women who did not leave the country (non-migrants) and were subject to restrictive family policies from 1974 to 2015 to those who moved to the United States (migrants) and were, thus, “emancipated” from these policies. We theoretically develop and empirically test the emancipation hypothesis that migrants should have a higher fertility than non-migrants, as well as an earlier timing of childbearing. This emancipation effect is hypothesized to decline across birth cohorts. We use data from the 2000 US census, the 2005 American Community Survey, the 2000 Chinese census, and the 2005 Chinese 1 percent Population Survey and discrete-time event history models to analyze first, second, and third births, and migration as joint processes, to account for selection effects. The results show that Chinese migrants to the United States had substantially higher childbearing probabilities after migration, compared with non-migrants in China, especially for second and third births. Moreover, our analyses indicate that the migration process is selective of migrants with lower fertility. Overall, the results show how international migration from China to the United States can lead to an increase in migrant women’s fertility, accounting for disruption, adaptation, and selection effects. The rapidly increased fertility after migration from China to the United States might have implications on other migration contexts where fertility in the origin country is dropping rapidly while that in the destination country is relatively stable.

scholarly journals H2-Bearing Damped Lyman-α Systems as Tracers of Cosmological Chemical Evolution

2004 ◽  
Vol 217 ◽  
pp. 252-257
Author(s):  
M. T. Murphy ◽  
S. J. Curran ◽  
J. K. Webb
Keyword(s):  
Chemical Evolution ◽  
Selection Effects ◽  
Host Galaxies ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Observational Selection ◽  
Host Type ◽  
Molecular Fraction ◽  
Magnitude Variation

The chemical abundances in damped Lyman-α systems (DLAs) show more than 2 orders of magnitude variation at a given epoch, possibly because DLAs arise in a wide variety of host galaxies. This could significantly bias estimates of chemical evolution. We explore the possibility that DLAs in which H2 absorption is detected may trace cosmological chemical evolution more reliably since they may comprise a narrower set of physical conditions. The 9 known H2 absorption systems support this hypothesis: metallicity exhibits a faster, more well-defined evolution with redshift than in the general DLA population. The dust-depletion factor and, particularly, H2 molecular fraction also show rapid increases with decreasing redshift. We comment on possible observational selection effects which may bias this evolution. Larger samples of H2-bearing DLAs are clearly required and may constrain evolution of the UV background and DLA galaxy host type with redshift.

scholarly journals Towards an Improved Model of the Galaxy

1998 ◽  
Vol 11 (1) ◽  
pp. 570-570
Author(s):  
Johan Holmberg ◽  
Lennart Lindegren ◽  
Chris Flynn
Keyword(s):  
Three Dimensional ◽  
Direct Determination ◽  
Galactic Structure ◽  
Open Clusters ◽  
Selection Effects ◽  
Observational Errors ◽  
Red Giant ◽  
Improved Model ◽  
First Time ◽  
Hr Diagram

We use the Hipparcos survey to derive an improved model of the local galactic structure. The availability of parallaxes for all the stars permits direct determination of stellar distributions, eliminating the basic indeterminacy of classical methods based on star counts. Hipparcos gives for the first time a truly three-dimensional view of the solar vicinity, and a complete, homogeneous and highly accurate set of magnitudes and colours. This means that new techniques can be applied in the treatment of the data which place strong constraints on a model that tries to describe the local Galactic structure. Here we investigate how well a static model of low complexitycan describe the Hipparcos observations. The interpretation of the Hipparcos data is complicated by various observational errors and selection effects that are hard to treat correctly. We do not try to correct the data, but instead use a model and subject this model to the same observational errors and selection effects. A model catalogue is created that can be compared with the observed catalogue directly in the observational domain, thereby eliminating the effects from various biases. Many features in the HR diagram are for the first time seen in field stars thanks to Hipparcos, such as the slanted red giant clump, previously seen in rich old open clusters such as Berkeley 18. This and other features ofthe observed HR diagram are well reproduced by the model thanks to the rather detailed modelling of the joint Mv/B — V distribution. Actually, separate distributions were derived for the three different components, disk, thick disk and halo, using the kinematic characteristics of the components to discriminate between them.

scholarly journals A statistical analysis of the nulling pulsar population

2021 ◽  
Vol 502 (4) ◽  
pp. 4669-4679
Author(s):  
Sofia Z Sheikh ◽  
Mariah G MacDonald
Keyword(s):  
Statistical Analysis ◽  
Pulse Width ◽  
Local Minimum ◽  
Broad Band ◽  
Selection Effects ◽  
Clustering Methods ◽  
Pulsar Emission ◽  
Spin Period ◽  
Null State ◽  
Linear Correlations

ABSTRACT Approximately 8 per cent of the ∼2800 known pulsars exhibit ‘nulling,’ a temporary broad-band cessation of normal pulsar emission. Nulling behaviour can be coarsely quantified by the nulling fraction, which describes the percentage of time a given pulsar will be found in a null state. In this paper, we perform the most thorough statistical analysis thus far of the properties of 141 known nulling pulsars. We find weak, non-linear correlations between nulling fraction and pulse width, as well as nulling fraction and spin period which could be attributed to selection effects. We also further investigate a recently hypothesized gap at 40 per cent nulling fraction. While a local minimum does exist in the distribution, we cannot confirm a consistent and unique break in the distribution when we investigate with univariate and multivariate clustering methods, nor can we prove the existence of two statistically distinct populations about this minimum. Using the same methods, we find that nulling pulsars are a statistically different population from normal, radio, non-nulling pulsars, which has never been quantitatively verified. In addition, we summarize the findings of the prior nulling pulsar statistics literature, which are notoriously contradictory. This study, in context, furthers the idea that nulling fraction alone does not contain enough information to describe the behaviour of a nulling pulsar and that other parameters such as null lengths and null randomness, in addition to a better understanding of selection effects, are required to fully understand this phenomenon.

Sign in / Sign up

Export Citation Format

Share Document