Does product complexity matter for competition in experimental retail markets?

We describe a first experiment on whether product complexity affects competition and consumers in retail markets. We are unable to detect a significant effect of product complexity on prices, except insofar as the demand elasticity for complex products is higher. However, there is qualified evidence that complex products have the potential to induce consumers to buy more than they would otherwise. In this sense, consumer exploitability in quantities cannot be ruled out. We also find evidence for shaping effects: consumers’ preferences are shaped by past experience with prices, and firms may in principle exploit this to sell more.     

Racial capitalism and STEM education in Chicago Public Schools

ABSTRACT

This article analyzes the role of STEM initiatives designed by city and corporate elites in a large urban district and outlines an alternative, grassroots vision for (STEM) education and city schools. Within a neoliberal context of gentrification, displacement, disinvestment, and privatization, STEM schools have become strategic components of Chicago’s ‘portfolio district’ that serve the interests of racial capitalism in three ways. First, STEM schools provide a claim to fairness in the midst of racist school closures. Second, STEM high schools are a corporate strategy for racially stratified labor force preparation that restricts curriculum and reifies tracking. Third, curriculum restriction prioritizes corporate interests over students’ capacity to shape their communities and the world. The authors draw on the wisdom of Chicago communities who have led resistance against corporate education reform to critique Chicago STEM policy and point to critical mathematics and science education as part of a model for sustainable community schools.     

Robust Bayesian model selection for variable clustering with the Gaussian graphical model

Statistics and Computing - Variable clustering is important for explanatory analysis. However, only few dedicated methods for variable clustering with the Gaussian graphical model have been...     

无锡市某区残疾人辅助器具需求分析

目的:探索不同状况下残疾人辅助器具的需求差异,找出原因,为制定辅助器具服务政策和合理配发辅助器具提供客观依据?方法:基于全国残疾人基本服务状况和需求专项调查,通过横断面调查获取无锡市某区9个街道(镇)残疾人及疑似残疾儿童的调查问卷6 188份?调查内容包含基本信息?残疾类别?残疾等级?教育文化程度等?采用SPSS22.0 统计软件进行Logistic回归分析?结果:残疾人的辅助器具需求受到残疾种类(P < 0.001)?残疾等级(P < 0.001)?年龄(P = 0.024)?就业情况(P = 0.002)和前一年是否获得辅具(P < 0.001)的影响,性别(P = 0.805)?婚姻状况(P = 0.459)?社保状况(P = 0.195)与教育文化状况(P =0.451)无影响作用?结论:听力?视力?肢体?多重残疾会导致辅助器具需求升高,重度残疾?儿童和老人?未就业和前一年获得辅具都能预示人群较高的辅具需求?     

有机硼交联HPG压裂液超低温破胶剂室内研究

对埋藏浅,油层温度低的油藏进行压裂改造,需解决压裂液低温破胶水化的问题。采用活化剂来提高过硫酸铵(APS),酶,胶囊破胶剂的低温破胶能力。通过对有机硼交联的羟丙基瓜胶(HPG)压裂液低温下破胶后粘度损失率的测定,筛选出用于50℃下的APS/活化剂破胶系统及胶囊破胶剂。结果表明:在APS/活化剂破胶系统的作用下,采用有机硼作交联剂的HPG压裂液在较低温度条件下能彻底破胶水化。     

Linear Increments with Non‐monotone Missing Data and Measurement Error

Linear increments (LI) are used to analyse repeated outcome data with missing values. Previously, two LI methods have been proposed, one allowing non‐monotone missingness but not independent measurement error and one allowing independent measurement error but only monotone missingness. In both, it was suggested that the expected increment could depend on current outcome. We show that LI can allow non‐monotone missingness and either independent measurement error of unknown variance or dependence of expected increment on current outcome but not both. A popular alternative to LI is a multivariate normal model ignoring the missingness pattern. This gives consistent estimation when data are normally distributed and missing at random (MAR). We clarify the relation between MAR and the assumptions of LI and show that for continuous outcomes multivariate normal estimators are also consistent under (non‐MAR and non‐normal) assumptions not much stronger than those of LI. Moreover, when missingness is non‐monotone, they are typically more efficient.     

Semiparametric Estimation of a Change-point for Recurrent Events Data

One particular recurrent events data scenario involves patients experiencing events according to a common intensity rate, and then a treatment may be applied. The treatment might be effective for a limited amount of time, so that the intensity rate would be expected to change abruptly when the effect of the treatment wears out. In particular, we allow models for the intensity rate, post-treatment, to be at first decreasing and then change to increasing (and vice versa). Two estimators of the location of this change are proposed.