改进的M/T法在电机测速中的应用

转速控制系统中,电机转速作为反馈量构成闭环控制。因此,电机转速测量的精度对控制系统性能有着至关重要的作用。文章采用基于一种精度得到较大提高的改进M/T法理论来设计的单片机来测量电机速度。在变频器控制电机中的实验结果表明,使用改进的M/T法测量精度高,测量范围广。     

Gender bias in job referrals: An experimental test

Employee referral programs, while efficient for the employer, have been shown to amplify sex-based occupational segregation in labor markets because of the tendency of workers to refer people of the same gender. We implement a controlled laboratory experiment that precludes any concern for network composition or reputation effects in referral choice. In this way, our experimental design allows us to disentangle statistical discrimination, preferences, and implicit same-gender bias. Our data suggest that women tend to favor women when choosing a candidate, whereas men do not attach much importance to the gender of potential candidates. We deduce from our various treatments that same-gender referrals are mainly driven by preferences in competitive environments and implicit same-gender bias in cooperative environments. Our findings add to the existing literature by highlighting that gendered networks alone fail to explain the observed gender homophily in referred-referrer pairs.     

What affects customer success when bargaining for a new car? Some empirical evidence

Data about 233 new car models were collected, and a measure of customer success in bargaining for a new car (alpha) was created by computing the ratio between the discount received on the manufacturer's suggested retail price (MSRP) and the negotiable range (MSRP − dealer's car cost). One hypothesis was that customers who purchase more expensive cars succeed less in bargaining because of their higher time value. A second hypothesis was that a positive correlation between the negotiable range and alpha should exist, because of either customer incentives to bargain or dealer's bargaining strategy. Both hypotheses were supported by the data.     

论穆旦1945年正面描写战争的诗——以《退伍》《农民兵》为例

穆旦在1945年这一特殊的年份下,写了一系列有关正面描写战争的诗歌。但这些诗歌并不是对战争做单一的描写,而是将其以往诗歌中的诸多特质,如,将关注底层、怀疑与反思精神等融入其中。穆旦通过《退伍》与《农民兵》展示了"多余"的退伍兵和"苦难"的农民兵两类士兵形象,完美地将直面战争、关注底层和思考战争融合到一起。对这两首直面战争、关注底层、充满怀疑与反思之作进行分析,可以为我们理解穆旦1945年的诗歌创作提供一个思考的角度。     

A Proposed Hybrid Effect Size Plus p-Value Criterion: Empirical Evidence Supporting its Use

ABSTRACT

When the editors of Basic and Applied Social Psychology effectively banned the use of null hypothesis significance testing (NHST) from articles published in their journal, it set off a fire-storm of discussions both supporting the decision and defending the utility of NHST in scientific research. At the heart of NHST is the p-value which is the probability of obtaining an effect equal to or more extreme than the one observed in the sample data, given the null hypothesis and other model assumptions. Although this is conceptually different from the probability of the null hypothesis being true, given the sample, p-values nonetheless can provide evidential information, toward making an inference about a parameter. Applying a 10,000-case simulation described in this article, the authors found that p-values’ inferential signals to either reject or not reject a null hypothesis about the mean (α?=?0.05) were consistent for almost 70% of the cases with the parameter’s true location for the sampled-from population. Success increases if a hybrid decision criterion, minimum effect size plus p-value (MESP), is used. Here, rejecting the null also requires the difference of the observed statistic from the exact null to be meaningfully large or practically significant, in the researcher’s judgment and experience. The simulation compares performances of several methods: from p-value and/or effect size-based, to confidence-interval based, under various conditions of true location of the mean, test power, and comparative sizes of the meaningful distance and population variability. For any inference procedure that outputs a binary indicator, like flagging whether a p-value is significant, the output of one single experiment is not sufficient evidence for a definitive conclusion. Yet, if a tool like MESP generates a relatively reliable signal and is used knowledgeably as part of a research process, it can provide useful information.     

Exact methods for testing homogeneity of proportions for multiple groups of paired binary data

We consider four exact procedures to test the homogeneity of proportions for correlated multiple clustered data. Exact procedures are compared with the asymptotic approach based on the score statistic. We use a real example from a double-blind clinical trial studying the treatment of otitis media to illustrate the various test procedures and provide extensive numerical studies to compare procedures with regards to Type I error rates and powers under the unconditional framework. The exact unconditional procedure based on estimation followed by maximization is generally more powerful than other procedures.     

恶之根源：《等待野蛮人》中的路西法效应 *

库切在《等待野蛮人》中展现了系统力量造就的“敌意想象”和情境力量场中的“去个人化”对施恶者人性和行为的强力影响，改变了人们对人性和罪恶行径的定势认知。虽然库切对人性之黑暗有着清晰的洞察，然而，他并没有对人性丧失信心。通过对主人公这一平凡英雄的刻画与褒扬，库切试图向人们传达：只要坚守人性之本分，人完全可以凭借自身意志力抵抗住外在力量的影响，避免走向恶之端。库切对罪恶和人性的深刻剖析显示其作为一名哲学作家的深度思辨。     

The rate of convergence to stationarity for M/G/1 models with admission controls via coupling

We study the workload processes of two M/G/1 queueing systems with restricted capacity: in Model 1 any service requirement that would exceed a certain capacity threshold is truncated; in Model 2 new arrivals do not enter the system if they have to wait more than a fixed threshold time in line. For Model 1 we obtain several results concerning the rate of convergence to equilibrium. In particular, we derive uniform bounds for geometric ergodicity with respect to certain subclasses. For Model 2 geometric ergodicity follows from the finiteness of the moment-generating function of the service time distribution. We derive bounds for the convergence rates in special cases. The proofs use the coupling method.     

Exact methods of testing the homogeneity of prevalences for correlated binary data

Correlated binary data arise in many ophthalmological and otolaryngological clinical trials. To test the homogeneity of prevalences among different groups is an important issue when conducting these trials. The equal correlation coefficients model proposed by Donner in 1989 is a popular model handling correlated binary data. The asymptotic chi-square test works well when the sample size is large. However, it would fail to maintain the type I error rate when the sample size is relatively small. In this paper, we propose several exact methods to deal with small sample scenarios. Their performances are compared with respect to type I error rate and power. The ‘M approach’ and the ‘E + M approach’ seem to outperform the others. A real work example is given to further explain how these approaches work. Finally, the computational efficiency of the exact methods is discussed as a pressing issue of future work.     

互文性视角下的《到灯塔去》解读

本文以格林兄弟的经典童话《渔夫和他的妻子》为切入点，运用互文性理论，解读伍尔芙夫人的代表作《到灯塔去》。通过分析发现，在这个被不断讲述的童话和现行文本之间存在着互文关系：《到灯塔去》就是一个重说了一遍的童话，第一讲述者是男人，即格林兄弟；第二讲述者是女人，即伍尔芙夫人，只不过，伍尔芙夫人改写了这篇被女性视作谎言的童话，并将其还原为故事的真实状态。