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A Note on the Minimax Solution for the Two-Stage Group Testing Problem
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| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 45-52 |
| Abstrak | : | Group testing is an active area of current research and has important applications in medicine, biotechnology, genetics, and product testing. There have been recent advances in design and estimation, but the simple Dorfman procedure introduced by R. Dorfman in Citation1943 is widely used in practice. In many practical situations, the exact value of the probability p of being affected is unknown. We present both minimax and Bayesian solutions for the group size problem when p is unknown. For unbounded p, we show that the minimax solution for group size is 8, while using a Bayesian strategy with Jeffreys’ prior results in a group size of 13. We also present solutions when p is bounded from above. For the practitioner, we propose strong justification for using a group size of between 8 and 13 when a constraint on p is not incorporated and provide useable code for computing the minimax group size under a constrained p. |
Maximizing Probability Bounds Under Moment-Matching Restrictions
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 41-44 |
| Abstrak | : | The problem of characterizing a distribution by its moments dates to work by Chebyshev in the mid-nineteenth century. There are clear (and close) connections with characteristic functions, moment spaces, quadrature, and other very classical mathematical pursuits. Lindsay and Basak posed the specific question of how far from normality could a distribution be if it matches k normal moments. They provided a bound on the maximal difference in cdfs, and implied that these bounds were attained. It will be shown here that in fact the bound is not attained if the number of even moments matched is odd. An explicit solution is developed as a symmetric distribution with a finite number of mass points when the number of even moments matched is even, and this bound for the even case is shown to hold as an explicit limit for the subsequent odd case. As Lindsay noted, the discrepancies can be sizable even for a moderate number of matched moments. Some comments on implications are proffered. |
Biostatistics Faculty and NIH Awards at U.S. Medical Schools
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 34-40 |
| Abstrak | : | Statistical principles and methods are critical to the success of biomedical and translational research. However, it is difficult to track and evaluate the monetary value of a biostatistician to a medical school (SoM). Limited published data on this topic are available, especially comparing across SoMs. Using National Institutes of Health (NIH) awards and American Association of Medical Colleges (AAMC) faculty counts data (2010–2013), together with online information on biostatistics faculty from 119 institutions across the country, we demonstrated that the number of biostatistics faculty was significantly positively associated with the amount of NIH awards, both as a school total and on a per faculty basis, across various sizes of U.S. SoMs. Biostatisticians, as a profession, should be proactive in communicating and advocating the value of their work and their unique contribution to the long-term success of a biomedical research enterprise. Supplementary materials for this article are available online. |
Monotone B-Spline Smoothing for a Generalized Linear Model Response
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 28-33 |
| Abstrak | : | Various methods have been proposed for smoothing under the monotonicity constraint. We review the literature and implement an approach of monotone smoothing with B-splines for a generalized linear model response. The approach is expressed as a quadratic programming problem and is easily solved using the statistical software R. In a simulation study, we find that the approach performs better than other approaches with much faster computation time. The approach can also be used for smoothing under other shape constraints or mixed constraints. Supplementary materials of the appendices and R code to implement the developed approach is available online. |
Did the Military Interventions in the Mexican Drug War Increase Violence?
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 17-27 |
| Abstrak | : | We analyze publicly available data to estimate the causal effects of military interventions on the homicide rates in certain problematic regions in Mexico. We use the Rubin causal model to compare the post-intervention homicide rate in each intervened region to the hypothetical homicide rate for that same year had the military intervention not taken place. Because the effect of a military intervention is not confined to the municipality subject to the intervention, a nonstandard definition of units is necessary to estimate the causal effect of the intervention under the standard no-interference assumption of stable-unit treatment value assumption (SUTVA). Donor pools are created for each missing potential outcome under no intervention, thereby allowing for the estimation of unit-level causal effects. A multiple imputation approach accounts for uncertainty about the missing potential outcomes. |
Ethical Numbers: Ethics Training in U.S. Graduate Statistics Programs, 2013–2014
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 11-16 |
| Abstrak | : | As important members of research teams, statisticians bear an ethical responsibility to analyze, interpret, and report data honestly and objectively. One way of reinforcing ethical responsibilities is through required courses covering a variety of ethics-related topics at the graduate level. We assessed ethics requirements for graduate-level statistics training programs in the United States for the 2013–2014 academic year using the websites of 88 universities, examining 103 biostatistics programs, and 136 statistics degree programs. We categorized programs’ ethics training requirements as required or not required. Thirty-one (35.1%) universities required an ethics course for at least some degree students. Sixty-two (25.5%) degree programs required an ethics course for at least some students. The majority (77.4%) of required courses were worth 0 or 1 credit. Of the 177 programs without an ethics requirement, 19 (10.7%) listed an ethics elective. Although a single ethics course is insufficient for instilling an ethical approach to science, degree programs that model expectations through coursework point to the value of ethics in science. More training programs should prepare statisticians to consider the ethical dimensions of their work through required coursework. Supplementary materials for this article are available online. |
The Absolute Difference Law For Expectations
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 8-10 |
| Abstrak | : | We revisit the addition law for expectations and present a sibling law: the absolute law for expectations. We show that these two laws and their corresponding laws for probabilities can be reconciled under a single framework. As an application, we use the absolute law for expectations to calculate the mean absolute deviation. Finally, we remark on a hidden point in a related article previously published on these pages; this will help readers to avoid a potential pitfall. |
Markov's Inequality and Chebyshev's Inequality for Tail Probabilities: A Sharper Image
| Pengarang | : | Joel E. Cohen |
| Nama Majalah/Jurnal | : | The American Statistician |
| Volume / Edisi | : | 69 (No. 1) |
| Halaman | : | 5-7 |
| Abstrak | : | Markov's inequality gives an upper bound on the probability that a nonnegative random variable takes large values. For example, if the random variable is the lifetime of a person or a machine, Markov's inequality says that the probability that an individual survives more than three times the average lifetime in the population of such individuals cannot exceed one-third. Here we give a simple, intuitive geometric interpretation and derivation of Markov's inequality. These results lead to inequalities sharper than Markov's when information about conditional expectations is available, as in reliability theory, demography, and actuarial mathematics. We use these results to sharpen Chebyshev's tail inequality also. |
Mental health help-seeking intentions among Chinese international students in the U.S. higher education system: The role of coping self-efficacy, social support, and stigma for seeking psychological help.
| Pengarang | : | Lian, Zi; Wallace, Barbara C.; Fullilove, Robert E. |
| Nama Majalah/Jurnal | : | Asian American Journal of Psychology |
| Volume / Edisi | : | 11 (No. 3) |
| Halaman | : | 147-157 |
| Abstrak | : | This study investigated the mental health help-seeking intentions and its correlates among Chinese international students in the U.S. higher education system. An analytic cross-sectional study was conducted. Recruitment of participants occurred via a social media campaign, and participants were invited to complete an online anonymous survey. A total of 222 Chinese international students participated in the study. The majority of the participants were female (65.3%), graduate students (84.7%), and the only child in the family (83.8%). The participants had a mean age of 23.75 years old. When encountering mental health-related problems, participants reported the highest help-seeking intentions for an intimate partner, parent, and friend. A higher level of general mental health help-seeking intentions was associated with a higher level of coping self-efficacy, a higher level of social support, a lower level of stigma, being undergraduate students, and having no history of full-time employment. These findings indicated the preferred sources for mental health help seeking and the need to improve the general mental health help seeking among Chinese international students. Culturally tailored programs are needed that take into consideration Chinese cultural attitudes and beliefs with regard to mental and emotional symptoms of distress. |
Major depressive disorder and dysthymia disparities between U.S. born and foreign born Chinese Americans.
| Pengarang | : | Sun, Fei; Lee, Jaewon; Liu, Sizhe; Wardian, Jana; Guo, Man. |
| Nama Majalah/Jurnal | : | Asian American Journal of Psychology |
| Volume / Edisi | : | 11 (No. 3) |
| Halaman | : | 138-146 |
| Abstrak | : | This study aimed to shed light on factors that contribute to the differences in lifetime major depressive disorder (MDD) and lifetime dysthymia between U.S.-born and foreign-born Chinese American adults. Secondary data on a nationally representative sample of 598 Chinese Americans were retrieved from the National Latino and Asian American Study. MDD and dysthymia over the lifetime were evaluated against the diagnostic criteria for Diagnostic and Statistical Manual of Mental Disorders (fourth edition). The prevalence rates of lifetime MDD and dysthymia were 11.5% and 1.8%, respectively. Being U.S.-born was associated with higher likelihood of lifetime MDD and dysthymia. U.S.-born Chinese Americans reported higher English language competence, greater family cohesion, more informal coping, and increased perceived discrimination compared to their foreign-born counterparts. Mediation analyses found that reliance on informal coping for emotional challenges partially explained why U.S.-born Chinese Americans had a higher degree of lifetime MDD. Despite greater acculturation, U.S.-born Chinese Americans are not better off than their foreign-born counterparts in terms of MDD and dysthymia disorders. Reliance on informal networks to manage emotional difficulties might not be ideal. Mental health education and intervention programs for Chinese residing in the United States should help prevent and negotiate stressors (e.g., family conflicts) as well as facilitate effective help-seeking for mental health challenges. |