Non-parametric estimation of an acceleration parameter

Let X₁,… X_m be a random sample of m failure times under normal conditions with the underlying distribution F(x) and Y₁,…,Y_n a random sample of n failure times under accelerated condititons with underlying distribution G(x);G(x)=1?[1?F(x)]^θ with θ being the unknown parameter under study.Define:U_ij=1 otherwise.The joint distribution of _ijdoes not involve the distribution F and thus can be used to estimate the acceleration parameter θ.The second approach for estimating θ is to use the ranks of the Y-observations in the combined X- and Y-samples.In this paper we establish that the rank of the Y-observations in the pooled sample form a sufficient statistic for the information contained in the U_ii 's about the parameter θ and that there does not exist an unbiassed estimator for the parameter θ.We also construct several estimators and confidence interavals for the parameter θ.     

Infant and child mortality in India: trends in inequalities across economic groups

This paper examines the trends in economic inequalities with respect to infant and child mortality in India using three rounds of the Indian National Family Health Survey conducted in 1992–1993, 1998–1999, and 2005–2006. The paper uses concentration index, and pooled discrete-time survival regression model to examine the aforementioned trends and regional patterns. The findings suggest a decreasing trend in economic inequality in infant mortality but an upward trend in economic inequality in child mortality in India. Economic inequalities in infant mortality have narrowed in the southern region, whereas they have widened in the western region and risen in the northern region. However, mixed trends in concentration indices were found in the different regions of India in the case of child mortality.     

Ethopolitics and the financial citizen

While personal debt has been the subject of intense research activity over the past decade, in particular from think tanks and government bodies, it remains relatively undertheorized and neglected in general by the social sciences. This article offers a novel theoretical frame for the analysis of personal debt – and personal overindebtedness in particular – by highlighting the construction of deviance from financial behavioural normativities. Using Nikolas Rose's concept of ‘ethopolitics’ to describe the relocation of government from questions of rational administration to those of everyday morality and ethics, this article presents two characterizations of deviance from an ethopolitical imaginary of financial citizenship: irresponsibility and incapability. From this framework, the article explores the nature of the state sponsored normalization of indebtedness and the stigmatization of overindebtedness as a corollary of ‘delinquent’ dispositions and dependencies. This article suggests that UK government policy concerning financial responsibility has been shaped by an ethopolitical imaginary of financial citizenship which is based upon a skewed understanding of structure and agency which has its parallel in the attribution of unemployment to ‘worklessness’.     

Impeding the Juggernaut of Innovation Diffusion: A Production‐Constrained Model

Models of innovation diffusion typically depict an inexorable momentum once the process begins to roll. Limited production capacity, however, can place a cap on this process, leading to waiting lines of potential customers, thus diminishing overall service quality and the speed of diffusion. Identifying the minimum production capacity needed for unimpeded and unimpaired diffusion can ensure that there are no customers waiting to adopt the product. We propose a production‐capacity‐constrained diffusion model that considers an exogenous industry production capacity and accounts for word‐of‐mouth effects from adopters as well as waiting customers. We derive analytical expressions for minimum capacity needed under multiple production scenarios. We present a dual‐objective non‐linear least squares procedure with large‐scale grid search for estimating the parameters. We apply our model to several new product innovation data sets, ranging from vacuum cleaners to sports utility vehicles in the United States to iPhones globally. Our estimates show that product shortages exist, ranging from mild to severe, in all of these product markets. We are able to corroborate some of our findings with independent external sources of evidence. We find that information on industry capacity can be recovered with as few as 5 years of sales data. Our model has practical implications for policy makers and can help equity analysts triangulate industry capacity better, particularly when such information is closely held.     

A model for estimating fecundability of the currently married woman from the data on her susceptibility status—A cohort approach

A probability model to estimate fecundability of a married woman has been proposed under some mild assumptions. It utilises the knowledge on the susceptibility status of the married women (including menstruation, menopause, pregnancy and amenorrhea) and therefore sets another approach for estimating fecundability. In addition, it is capable of predicting the parity, proportion of foetal losses, fecundability and incidence of secondary sterility. The problem of finding out the consistent estimates of the parameters in the distribution is discussed in section 4. For illustra-tion, the model is applied to a set of simulated data after simplifying many assumptions of the model     

Sequential estimation of the sum of sinusoidal model parameters

Estimating the parameters of the sum of a sinusoidal model in presence of additive noise is a classical problem. It is well known to be a difficult problem when the two adjacent frequencies are not well separated or when the number of components is very large. In this paper we propose a simple sequential procedure to estimate the unknown frequencies and amplitudes of the sinusoidal signals. It is observed that if there are p components in the signal then at the k  th (k?p)$(k?p)$ stage our procedure produces strongly consistent estimators of the k   dominant sinusoids. For k>p$k>p$, the amplitude estimators converge to zero almost surely. Asymptotic distribution of the proposed estimators is also established and it is observed that it coincides with the asymptotic distribution of the least squares estimators. Numerical simulations are performed to observe the performance of the proposed estimators for different sample sizes and for different models. One ECG data and one synthesized data are analyzed for illustrative purpose.     

The Sensitivity of Detrended Long-Memory Processes

Long-memory tests are often complicated by the presence of deterministic trends. Hence, an additional step of detrending the data is necessary. The typical way to detrend a suspected long-memory series is to use OLS or BSP residuals. Applying the method of sensitivity analysis we address the of question of how robust these residuals are in presence of potential long memory components. Unlike short-memory ARMA process long-memory I(d) processes causes sensitivity to OLS/BSP residuals. Therefore, we develop a finite sample measure of the sensitivity of a detrended series based on the residuals. Based on our sensitivity measure we propose a “rule of thumb” for practitioners to choose between the two methods of detrending, has been provided in this article.     

Scheduling online advertisements to maximize revenue under variable display frequency

The online advertising industry realized annual revenues estimated at over $26 billion, in the United States alone, in 2010. Banner advertising accounts for an estimated 23% of all online advertising revenues. Publishers of banner advertisements face a scheduling optimization problem on a daily basis. Several papers in the literature have proposed mathematical models and solution approaches to address a publisher's banner advertisement scheduling problem and the problem has been shown to be NP-hard. In this paper we propose a new model variation for the problem, which incorporates variable display frequencies. We find that the variable-display frequency model provides significantly improved space utilization relative to the fixed-display frequency model and consequently higher revenues for the publishers.     

Systematic and nonrandom sampling in the presence of linear trends

In the case of a finite population with a linear trend, improvements in estimation procedures are suggested for several well-known systematic samplingschemes. The use of the least squares regression estimator is examined and a sampling scheme which reduces its expected mean squared error is proposed.     

Supplemental Retirement Savings Plans in the Public Sector: Participation and Contribution Decisions by School Personnel

Virtually all full-time state and local government employees are covered by a retirement plan, typically a defined benefit plan, in which they are required to participate. In addition, most school employees have the option of choosing to contribute to a voluntary retirement savings plan offered by their school district. Relative to private sector workers, public employees face an expanded choice of retirement savings plans. Federal tax policies allow state and local governments the opportunity to offer both 401(k) plans and 457 plans to their employees. In addition to these plans, public schools and certain other organizations can offer 403(b) plans to their employees. This paper examines the decision to participate in a voluntary savings plan and the level of contributions for those that enroll in at least one of the plans. The analysis begins by describing the savings options available to public school employees and how these plans differ. The findings indicate that the same economic and demographic factors that influence saving decisions by private workers also drive the decisions of school employees. The three savings plans offered to public employees have many similar characteristics; however, several differences in the plans imply that certain workers may prefer one plan type over the others. Probit and Tobit models of participation in any plan and total annual contributions are estimated. Finally, we estimate the determinants of the decision to choose any one or a combination of savings plans.