Analysis of proportions for clustered binary data in the presence of unequal dispersions

This paper investigates the test procedures for testing the homogeneity of the proportions in the analysis of clustered binary data in the context of unequal dispersions across the treatment groups. We introduce a simple test procedure based on adjusted proportions using a sandwich estimator of the variance of the proportion estimators obtained by the generalized estimating equations approach of Zeger and Liang (1986) [Biometrics 42, 121-130]. We also extend the exiting test procedures of testing the hypothesis of proportions in this context. These test procedures are then compared, by simulations, in terms of size and power. Moreover, we derive the score test for testing the homogeneity of the dispersion parameters among several groups of clustered binary data. An illustrative application of the recommended test procedures is also presented.     

Infant death clustering in families: magnitude, causes, and the influence of better health services, Bangladesh 1982-2005

This analysis of infant mortality in Bangladesh focuses on explaining death clustering within families, using prospective data from a rural region in Bangladesh, split into areas with and without extensive health services (the area covered by the International Centre for Diarrhoeal Disease Research and the comparison area, respectively). The modelling framework distinguishes between two explanations of death clustering: (observed and unobserved) heterogeneity across families and a causal 'scarring' effect of the death of one infant on the survival chances of the next to be born. Keeping observed and unobserved characteristics constant, we find scarring in the comparison area only. There the likelihood of infant death is about 29 per cent greater if the previous sibling died in infancy than otherwise. This effect mainly works through birth intervals: infant deaths are followed by shorter birth intervals, which increases the risk of infant death for the next child.     

A GENERALIZED TWO-STAGE RANDOMIZED RESPONSE PROCEDURE IN COMPLEX SAMPLE SURVEYS

The randomized response (RR) technique pioneered by Warner, S.L. (1965) [Randomised response: a survey technique for eliminating evasive answer bias. J. Amer. Statist. Assoc. 60 , 63–69] is a useful tool in estimating the proportion of persons in a community bearing sensitive or socially disapproved characteristics. Mangat, N.S. & Singh, R. (1990) [An alternative rendomized response procedure. Biometrika 77 , 439–442] proposed a modification of Warner's procedure by using two RR techniques. Presented here is a generalized two‐stage RR procedure and derivation of the condition under which the proposed procedure produces a more precise estimator of the population parameter. A comparative study on the performance of this two‐stage procedure and conventional RR techniques, assuming that the respondents' jeopardy level in this proposed method remains the same as that offered by the traditional RR procedures, is also reported. In addition, a numerical example compares the efficiency of the proposed method with the traditional RR procedures.     

Social Coping and Life Satisfaction in Adolescents

This study examined the relationships among early adolescent social coping behavior and measures of subjective well-being, specifically global life satisfaction and friend satisfaction. A total of 1,011 students in grades 7–8 at a southeastern US middle school completed measures of global life satisfaction, friend satisfaction and coping, on two occasions, 5 months apart. Social support seeking coping behavior at Time 1, but not problem-solving, distancing, internalizing or externalizing coping behaviors at Time 1, uniquely predicted global life satisfaction and friend satisfaction at Time 2. Implications for research and promoting adolescent well-being are discussed.     

Optimal weighing designs with a string property

We consider the usual (spring balance) weighing design set-up with the design matrix having a string property meaning thereby that in every row of it, there is exactly one run of 1's (the rest of the elements being 0's). We have investigated some interesting features of such matrices and used them in deriving various optimality results.     

“I Amn Not a Utistivc on Thje Typ” (“I'm Not Autistic on the Typewriter”)

Facilitated communication involves hand-over-hand or hand-on-forearm support of students as they communicate through pointing at pictures, letters or other objects. Over time, it is expected that the hand and arm support can be faded back. This observational study describes an effort to introduce facilitated communication to 22 students, ranging in age from 3 years 10 months to 21 years, in several US public schools. The students are all labeled autistic and do not speak or speak only with echolalic phrases. The findings include observations of the students communicating with facilitation, language samples, and conversations by the students. The students reveal unexpected literacy and numeracy skills. The appearance of these abilities raises a number of questions concerning prior assumptions about autism, communication, independence and interdependence, and the education of students with and without disabilities.