Adaptive two-treatment two-period crossover design for binary treatment responses incorporating carry-over effects

Adaptive designs are sometimes used in a phase III clinical trial with the goal of allocating a larger number of patients to the better treatment. In the present paper we use some adaptive designs in a two-treatment two-period crossover trial in the presence of possible carry-over effects, where the treatment responses are binary. We use some simple designs to choose between the possible treatment combinations AA, AB, BA or BB. The goal is to use the better treatment a larger proportion of times. We calculate the allocation proportions to the possible treatment combinations and their standard deviations. We also investigate related inferential problems, for which related asymptotics are derived. The proposed procedure is compared with a possible competitor. Finally we use real data sets to illustrate the applicability of our proposed design.     

Cross-over Designs in the Presence of Higher Order Carry-overs

In cross-over experiments, where different treatments are applied successively to the same experimental unit over a number of time periods, it is often expected that a treatment has a carry-over effect in one or more periods following its period of application. The effect of interaction between the treatments in the successive periods may also affect the response. However, it seems that all systematic studies of the optimality properties of cross-over designs have been done under models where carry-over effects are assumed to persist for only one subsequent period. This paper proposes a model which allows for the possible presence of carry-over effects up to k subsequent periods, together with all the interactions between treatments applied at k + 1 successive periods. This model allows the practitioner to choose k for any experiment according to the requirements of that particular experiment. Under this model, the cross-over designs are studied and the class of optimal designs is obtained. A method of constructing these optimal designs is also given.     

Measurement of occupational mobility using semi-markov models

As proposed by Bartholomew (1967), occupational mobility should better be represented by semi-Markov processes. In the present paper attempts have been made to develop some new measures of occupational mobility in terms of serai-Markov processes and their values have been studied in the three extreme situations of interest.     

Estimation procedures for grouped data – a comparative study

Interval-censored data are very common in the reliability and lifetime data analysis. This paper investigates the performance of different estimation procedures for a special type of interval-censored data, i.e. grouped data, from three widely used lifetime distributions. The approaches considered here include the maximum likelihood estimation, the minimum distance estimation based on chi-square criterion, the moment estimation based on imputation (IM) method and an ad hoc estimation procedure. Although IM-based techniques are extensively used recently, we show that this method is not always effective. It is found that the ad hoc estimation procedure is equivalent to the minimum distance estimation with another distance metric and more effective in the simulation. The procedures of different approaches are presented and their performances are investigated by Monte Carlo simulation for various combinations of sample sizes and parameter settings. The numerical results provide guidelines to analyse grouped data for practitioners when they need to choose a good estimation approach.     

Role of women in schooling and child labour decision: the case of urban boys in India

This paper uses household level data from National Sample Survey Organization (NSSO) of India, the 55th round (1999–2000), to show that for urban male children there exists significant wage incentive for schooling, though school dropout rate and child labour incidence are not so small. The parents’ level of education plays an important role in reducing this tendency; thus establishing the linkage between social and human capital outcomes in the family. We also look at the incidence of harmful and manual occupations among the child labour. Mother’s education now appears as a very important factor in curbing these incidences; supporting earlier findings that women’s empowerment (one important indicator of which would be female educational level) is indeed instrumental in increasing parental awareness.     

TECHNIQUES OF COVARIANCE STRUCTURAL ANALYSIS1

The paper delineates the scope and important features of covariance structural analysis in which some pattern can be postulated a priori for the covariance matrix. The coverage given also includes a brief review of the published work in this area with illustration of statistical tests based, on principles of maximum likelihood and union-intersection. Few results on the computational ease under the assumption of particular covariance structures are reported. A few unsolved problems in the area of structural analysis are briefly mentioned.     

Multivariate relationships between modernity value orientations and family planning indicators

Using canonical correlation techniques in the analysis of data collected from interviews with 1,737 married women of three Indian states, this paper evaluated three modernity value orientations—subjective efficacy, openness to change, and propensity to plan—as predictors of a set of four family planning indicators. The analysis revealed that, in Haryana, both subjective efficacy and openness to change were related to family planning knowledge and attitudes as well as to favorability toward small family size. Propensity to plan was related to adoption. In rural Tamil Nadu, subjective efficacy and openness to change were related essentially to family planning attitudes, whereas in urban Tamil Nadu they were strongly related to adoption. In the latter area, the best linear association between the modernity variables (predictor set) and the family planning variables (criterion set) resulted when the criterion set was so weighted that it involved a large amount of adoption and a moderate amount of contraceptive knowledge and attitudes. Thus, in urban Tamil Nadu, the four family planning variables seemed to cohere, reflecting cognitive, attitudinal, and behavioral consistency. Except in Meghalaya, it appears that married women with higher subjective efficacy, openness to change, and planning tendency may be more likely than others to translate their family planning knowledge and favorability toward small family size into action, under suitable conditions. Some of the implications of the findings are discussed.The author is affiliated with the Council for Social Development, 53 Lodi Estate, New Delhi, 110003, India.     

On A Symmetric Measure of Occupational Segregation

Occupational segregation according to sex iswidely prevalent in almost allcountries. This paper suggests and characterizes a symmetric measure ofsegregation. This measure was originallyproposed in a different situation byJeffreys (1946). We also provide twonumerical illustrations of changein segregation over time.     

Estimation op parameters in finite mixtures of exponential families from censored data

A general successive substitutions' scheme is developed to estimate parameters in a finite mixture of distributions from the exponential family, based on censored data. It is assumed that the data can be grouped in the first class and the number of observations in each of the remaining classes are known Examples from Poisson Exponential and Normal distributions are given A small simulation exercise has also been carried out for the mixture of two one parameter exponential population.