Testing hypotheses for the growth curve model when the data are incomplete

Kleinbaum (1973) developed a generalized growth curve model for analyzing incomplete longitudinal data. In this paper the small sample properties of several related test statistics are investigated via Monte Carlo techniques. The covariance matrix is estimated by each of three non-iterative methods. The null and non-null distributions of these test statistics are examined.     

STRANGE YET STYLISH HEADGEAR VR consumption and the construction of gender

This article examines how gender is inscribed and reproduced in the consumption of Virtual Reality (VR) technologies. The focus is on how virtual reality systems become embedded in 'everyday life' through leisure and consumption, and how the spectacles and disciplines associated with consumption sites produce gendered virtual subjects. Studies of new communications technologies have tended to polarize between 'cyberpunk'/'cyberfeminist' visions of bodily transcendence in 'cyberspaces', and the critique of such visions from social theorists who focus on the reproduction of social and cultural inequalities through technical systems. These approaches tend to neglect the specific sites in which the social relations of VR are played out. A 'multi-sited' ethnographic study of immersive virtual reality systems is the basis for discussion of how virtual reality technologies produce gender in specific sites. Virtual systems are positioned and used differently in various locales such as arcades and art galleries, bars and theme parks and cafes. The article discusses the practices of consumption which (re)produce and maintain conventional bodily and subjective boundaries. What relationships are becoming institutionalized? Are new conventions of gender created in these consumption relationships? The construction of spectacle and space, and the specific bodily disciplines required for participation in virtual realities in locations of consumption is particularly important in the formation of gender dynamics. Multiple subject positions are offered through competing technical, economic and cultural practices in diverse sites. These positions can establish new conventions of virtual identities and experiences, but also remain shot through with familiar operational categories of gendered identities and bodily practices. This article argues that immersive virtual reality technologies cannot be understood without some consideration of the locales in which they are embedded, and the social identities they make possible or constrain. A local, reflexive and feminist orientation assists in understanding the gendered dynamics associated with 'becoming virtual'.     

Assessing program impact using latent growth modeling: a primer for the evaluator

Latent growth modeling (LGM) has emerged as a flexible analytic technique for modeling change over time because it can describe developmental processes at both the inter- and intra-individual levels. The LGM method can also provide a means for testing the contribution of other variables in order to explain variability in growth trajectories. This paper didactically illustrates the use of LGM as an analytical tool in program evaluation. Specifically, a hypothetical evaluation of a high school drug prevention program was used to demonstrate: (a) how LGM can be used to assess the longitudinal impact of a prevention program by comparing treatment and control populations with respect to individual differences in initial status and in rate of change; and (b) how predictors of initial status (post-intervention) and growth selected on the basis of a particular program theory can be incorporated in the model to explain program impact. Some advantages and limitations of using LGM in program evaluation are highlighted.     

Then press enter: digital payment technology and the history of telephone interface

The internet and other digital networks in the U.S. (and beyond) remain essentially an upgrade of the national telephone network built by AT&T over the first half of the twentieth century, and digital payment remains tethered to telephony at the level of infrastructure. Telephone history also continues to inform digital payment at the level of interface. Debit card readers feature a keypad nearly identical to those introduced (also by AT&T) to the dialling public a half-century ago on touch-tone telephones. In this essay I highlight the development of the touch-tone keypad as a transformative payment technology. There have been three great leaps forward in the history of telephone interface: the dial, the keypad and the touch screen. Each corresponds to a period of technological transformation in the telephone industry and society more broadly: the rotary dial and automation, touch-tone keypads and digitization, and touch screens and computerization. The successful careers of the dial and the keypad, especially when read in tandem, suggest that touch screens will alter the everyday economics of retail payment even more radically than its predecessors. I also describe a broader trajectory of digital naturalization, whereby telephone numbers have proliferated into a personal identification number, passwords and a plethora of personalized information. Payments increasingly circulate today as subsets of personal information within the vast sea of big data. Payment apps are demonstrating a capacity to reorganize retail transactions on a scale as vast as any technology since the cash register. The history of retail payment finds the point of sale heading from the till into shoppers’ pockets. As a result, consumers are increasingly shouldering the costs of purchasing, maintaining, upgrading and securing the technology used for everyday transactions.     

近代早期城市的能源贸易与能源消费问题——以英格兰海煤为中心

中世纪至近代早期,海煤逐渐发展成为英格兰重要的贸易商品。贸易交换的增加,带动了英格兰的海煤消费。因此有学者认为,英格兰近代早期的城市污染与海煤的贸易和使用有密切关系。通过梳理英格兰海煤的贸易轨迹,得知近代早期英格兰海煤的贸易特点:以纽卡斯尔和布里斯托尔为典型的出口港口,以伦敦为典型的进口港口。近代早期英格兰的城市污染,尽管有消费海煤带来的影响,但二者之间并不存在明显的直接相关。海煤在英格兰近代化的历程中发挥重要的积极作用。     

试论《贵妇的画像》中伊莎贝尔的成长

《贵妇的画像》是19世纪末美国著名小说家亨利·詹姆斯的杰作之一,同时也是其创作早期代表作,是美国现代小说的一个里程碑式的作品,具有较强的可读性。这部作品结构严谨、内涵丰富,以精巧的笔触对女性的心理进行了细致入微的刻画。本文通过《贵妇的画像》这本小说,对主人伊莎贝尔·阿切尔的成长进行了深入探讨。     

中国能源消费静态依赖与动态发展——基于30个省市数据综列协整分析

本文以我国30个省市为横截单元、以1995-2005年时序数据组成综列数据,建立我国省市能源消费的综列协整模型,通过综列单位根和综列协整检验,结果表明,我国各省市的能源消费与经济增长和能源效率之间存在长期均衡。基于这一结论,揭示各省市能源消费静态依赖与动态发展特征,并给出政策建议。     

Exponential Growth Model: From Horizontal to Linear Asymptote

We present a smooth function that can be used as regression curve for modeling growth phenomena requiring an increasing curvilinear concave asymptote. This model is obtained as the product of a concave asymptotic curve and the exponential model. In addition to its increasing character with a curvilinear asymptote, including horizontal or linear increasing asymptote, the resulting model provides curves with a single inflection point. Numerical examples are presented.     

Estimating the Continuous-Time Consumption-Based Asset-Pricing Model

The consumption-based asset-pricing model predicts that excess yields are determined by the market's degree of relative risk aversion and by the covariances of per capita consumption growth with asset returns. Estimation and testing are complicated by the fact that the model's predictions relate to the instantaneous flow of consumption and point-in-time asset values, but only data on the integral or time average of the consumption flow are available. This article shows how to take account of the effects of time averaging on the covariances. We estimate the model's parameters and test the overidentifying restrictions using six different data sets.