Infants’ abilities to respond to cues for joint attention vary by family socioeconomic status

The influence of socioeconomic variability on language and cognitive development is present from toddlerhood to adolescence and calls for investigating its earliest manifestation. Response to joint attention (RJA) abilities constitute a foundational developmental milestone that are associated with future language, cognitive, and social skills. How aspects of the family home environment shape RJA skills is relatively unknown. We investigated associations between family socioeconomic status (SES) —both parent education and family percentage of the federal poverty level (FPL)— parent depressive and anxiety symptoms and infant RJA performance in a cross-sectional sample of 173 infants aged 8–18 months and their parents from a variety of socioeconomic backgrounds. Results suggest that, correcting for age and receptive language, infants in families with greater economic resources respond to relatively less redundant, more sophisticated cues for joint attention. Although parent depressive and anxiety symptoms are negatively correlated with SES, parent depressive and anxiety symptoms were not associated with infant RJA. These findings provide evidence of SES-related differences in social cognitive development as early as infancy, calling on policymakers to address the inequities in the current socioeconomic landscape of the United States.     

OptBand: optimization-based confidence bands for functions to characterize time-to-event distributions

Classical simultaneous confidence bands for survival functions (i.e., Hall–Wellner, equal precision, and empirical likelihood bands) are derived from transformations of the asymptotic Brownian nature of the Nelson–Aalen or Kaplan–Meier estimators. Due to the properties of Brownian motion, a theoretical derivation of the highest confidence density region cannot be obtained in closed form. Instead, we provide confidence bands derived from a related optimization problem with local time processes. These bands can be applied to the one-sample problem regarding both cumulative hazard and survival functions. In addition, we present a solution to the two-sample problem for testing differences in cumulative hazard functions. The finite sample performance of the proposed method is assessed by Monte Carlo simulation studies. The proposed bands are applied to clinical trial data to assess survival times for primary biliary cirrhosis patients treated with D-penicillamine.

     

Payday lenders and economically distressed communities: A spatial analysis of financial predation

The payday lending industry has grown considerably in recent years, reflecting both widespread economic insecurity and market neglect by the traditional banking sector. Outlets are now commonplace in many communities across America. Accused by many of predatory practices, payday lenders can be viewed as financial hazards in already economically distressed communities. Using a Geographic Information System (GIS) and associated statistical analyses, this paper examines the social ecology of payday lending along the Front Range communities of Colorado. Comparison of means and logistic regression results reveal how communities’ composition by class, occupation, race/ethnicity, nativity, age, and military affiliation affect their likelihood of hosting payday lending.     

What Does it Mean to Listen to People with Dementia?

A total of 19 people with dementia were interviewed as part of a study into unmet respite care need amongst caregivers and day-care attenders in Sheffield. Some important contextual debates associated with conducting social research with people with dementia are considered. These include informed consent, competency, and how the interests of caregivers and people with dementia are bound together. A form of process consent was used in conducting semi-structured interviews with day-care attenders. Day-care attenders spoke about 'being here' in a number of ways. These include their initial experiences, their sources of satisfaction and their sense of being in families. These substantive findings and the associated methodological insights suggest day-care attenders have important things to say as service-users if appropriate strategies for listening are employed. Service-providers can collaborate imaginatively with day-care attenders to actively explore how care might be shaped by the experiences of persons with dementia.     

Promotions and the pattern of grocery shopping time

The histograms of interpurchase times for frequently purchased packaged goods have consistently shown pronounced seven-day cycles. Evidence supports that the weekly spike phenomenon is the result of consumers' regular shopping trip schedules. We explore the implications of this peculiar regularity on the issue of consumer purchase timing acceleration. Data for five product categories are examined. Promotions are found to have little effect in accelerating purchase timing. In contrast, conventional interpurchase time models are shown to overstate the effect of promotions.     

Subterranean termites in the urban landscape: Understanding their social structure is the key to successfully implementing population management using bait technology

Subterranean termites will likely continue to be major economic insect pests in the urban environment. Public concerns about pesticide use will not abate but continue to drive development and implementation of environmentally more acceptable control strategies for subterranean termites. Termite baits are a promising alternative to soil termiticide treatments for protection of structures, but the correlation between killing termites in the landscape and protecting structures is tenuous given our current understanding of termite biology. We discuss the problems associated with defining the efficacy of termite bait products in regard to determining termite population parameters in the field. This discussion is in the form of six case histories involving measures of termite activity and relatedness taken over a three-year period. Our findings highlight the need to include control populations in studies of termite bait efficacy, the mobility of termite populations over time, the importance of defining the techniques used to describe termite colony associations, and the need to use a multidisciplinary research approach in addressing the question of termite social structure.     

Ordered ranked set samples and applications to inference

Ranked set sampling (RSS) was first proposed by McIntyre [1952. A method for unbiased selective sampling, using ranked sets. Australian J. Agricultural Res. 3, 385–390] as an effective way to estimate the unknown population mean. Chuiv and Sinha [1998. On some aspects of ranked set sampling in parametric estimation. In: Balakrishnan, N., Rao, C.R. (Eds.), Handbook of Statistics, vol. 17. Elsevier, Amsterdam, pp. 337–377] and Chen et al. [2004. Ranked Set Sampling—Theory and Application. Lecture Notes in Statistics, vol. 176. Springer, New York] have provided excellent surveys of RSS and various inferential results based on RSS. In this paper, we use the idea of order statistics from independent and non-identically distributed (INID) random variables to propose ordered ranked set sampling (ORSS) and then develop optimal linear inference based on ORSS. We determine the best linear unbiased estimators based on ORSS (BLUE-ORSS) and show that they are more efficient than BLUE-RSS for the two-parameter exponential, normal and logistic distributions. Although this is not the case for the one-parameter exponential distribution, the relative efficiency of the BLUE-ORSS (to BLUE-RSS) is very close to 1. Furthermore, we compare both BLUE-ORSS and BLUE-RSS with the BLUE based on order statistics from a simple random sample (BLUE-OS). We show that BLUE-ORSS is uniformly better than BLUE-OS, while BLUE-RSS is not as efficient as BLUE-OS for small sample sizes (n<5$n<5$).     

Starting Behind: A Comparative Analysis of the Academic Standing of Students Entering Charter Schools*

Objectives. The purpose of this study is to assess if students enter charter schools at an academic disadvantage compared to students who make other types of school‐choice decisions, such as transferring between district schools, from a charter to a district school, or staying in the same school. We assess the demographic and academic characteristics of students prior to choosing to attend a charter school in comparison to students who made other types of school‐choice decisions and broaden the operational definition of a “disadvantaged” student when exploring differences between charter and district students to include academic achievement prior to entering a school. Methods. The analysis is conducted with student‐level panel data and a progressive series of ANCOVA models that were estimated using ordinary least squares (OLS) regression. This methodology allows for a comparison of the mean differences in academic achievement among students who made different types of school‐choice decisions while controlling for student‐level covariates. Results. Students who transferred from district to charter schools had the lowest levels of prior academic achievement compared to students who made other types of choice decisions. Conclusions. When Arizona charter authorizers face the deluge of renewal decisions that are approaching, the quality of education available to the next generation of charter school students is at stake. Renewal decisions will impact what choices are available going forward and, given the comparative academic disadvantage of charter school students prior to entering, those decisions should take into consideration the starting point for students entering charter schools.     

Causes of ambiguity aversion: Known versus unknown preferences

Ambiguity aversion appears to have subtle psychological causes. Curley, Yates, and Abrams found that the fear of negative evaluation by others (FNE) increases ambiguity aversion. This paper introduces a design in which preferences can be private information of individuals, so that FNE can be avoided entirely. Thus, we can completely control for FNE and other social factors, and can determine exactly to what extent ambiguity aversion is driven by such social factors. In our experiment ambiguity aversion, while appearing as commonly found in the presence of FNE, disappears entirely if FNE is eliminated. Implications are discussed.      

Gender issues in social security policy of developing countries: Lessons from the Kerala experience

This paper is based on the premise that labour market conditions are critical in shaping access to social security benefits. Women's entitlement to long-term social security is in many respects different from that of men on account of the assumptions which pervade the system about gender roles, labour market conditions, and outcomes. The Indian state of Kerala has made great strides in formulating various schemes for workers in the informal sector, but gender concerns in social security are in want of attention in the light of demographic pressures, fiscal constraints and changes in the global economy.