Optimal spacing of quantiles for the estimation of the mixing parameters in a mixture of two exponential distributions

Methods for estimating the mixing parameters in a mixture of two exponential distributions are proposed. The estimators proposed are consistent and BAN(best asymptotically normal). The optimal spacings for estimating these mixture parameters are calculated.     

A survey of tests for exponentiality

A wide selection of tests for exponentiality is discussed and compared. Power computations, using simulations, were done for each procedure. Certain tests (e.g. Gnedenko (1969), Lin and Mudholkar (1980), Harris (1376), Cox and Oakes (1384), and Deshpande (1983)) performed well for alternative distributions with non-monotonic hazard rates, while others (e.g. Deshpande (1983), Gail and Gastwirth (1978), Kolmogorov-Smirnov (LillViefors (1969)), Hahn and Shapiro (1967), Hollander and Proschan (1972), and Cox and Oakes (1984)) fared well for monotonic hazard rates. Of all the procedures compared, the score test presented in Cox and Oakes (1984) appears to be the best if one does not have a particular alternative in mind.     

A new goodness of fit test for the equality of multinomial cell probabilities versus trend alternatives

In this paper, a new test statistic is presented for testing the null hypothesis of equal multinomial cell probabilities versus various trend alternatives. Exact asymptotic critical values are obtained, The power of the test is compared with several other statistics considered by Choulakian et al (1995), The test is shown to have better power for certain trend alternatives.     

Genealogies and Gene-ideologies: The Legitimacy of the Beta Israel (Falasha)

The migration of the vast majority of Beta Israel (Falasha) to Israel has been accompanied by major shifts in the discourse regarding their ‘Jewishness’ and ‘Ethiopian-ness’. This article discusses the adoption of traditions of Danite descent in place of traditions of Solomonic descent and the emergence of genetics as the most important identity marker, replacing reckonings of lineage. The first shift is connected to the migration of the Beta Israel from Ethiopia to Israel; the second to changing concepts of what represents ‘proof’ of identity in the modern and post-modern world.     

Adaptive sampling without replacement of clusters

In a common form of adaptive cluster sampling, an initial sample of units is selected by random sampling without replacement and, whenever the observed value of the unit is sufficiently high, its neighboring units are added to the sample, with the process of adding neighbors repeated if any of the added units are also high valued. In this way, an initial selection of a high-valued unit results in the addition of the entire network of surrounding high-valued units and some low-valued “edge” units where sampling stops. Repeat selections can occur when more than one initially selected unit is in the same network or when an edge unit is shared by more than one added network. Adaptive sampling without replacement of networks avoids some of this repeat selection by sequentially selecting initial sample units only from the part of the population not already in any selected network. The design proposed in this paper carries this step further by selecting initial units only from the population, exclusive of any previously selected networks or edge units.     

Three-level main-effects designs exploiting prior information about model uncertainty

To explore the projection efficiency of a design, Tsai, et al [2000. Projective three-level main effects designs robust to model uncertainty. Biometrika 87, 467–475] introduced the Q criterion to compare three-level main-effects designs for quantitative factors that allow the consideration of interactions in addition to main effects. In this paper, we extend their method and focus on the case in which experimenters have some prior knowledge, in advance of running the experiment, about the probabilities of effects being non-negligible. A criterion which incorporates experimenters’ prior beliefs about the importance of each effect is introduced to compare orthogonal, or nearly orthogonal, main effects designs with robustness to interactions as a secondary consideration. We show that this criterion, exploiting prior information about model uncertainty, can lead to more appropriate designs reflecting experimenters’ prior beliefs.     

A Diversity Index for Model Space Selection in the Estimation of Benchmark and Infectious Doses via Model Averaging

In chemical and microbial risk assessments, risk assessors fit dose‐response models to high‐dose data and extrapolate downward to risk levels in the range of 1–10%. Although multiple dose‐response models may be able to fit the data adequately in the experimental range, the estimated effective dose (ED) corresponding to an extremely small risk can be substantially different from model to model. In this respect, model averaging (MA) provides more robustness than a single dose‐response model in the point and interval estimation of an ED. In MA, accounting for both data uncertainty and model uncertainty is crucial, but addressing model uncertainty is not achieved simply by increasing the number of models in a model space. A plausible set of models for MA can be characterized by goodness of fit and diversity surrounding the truth. We propose a diversity index (DI) to balance between these two characteristics in model space selection. It addresses a collective property of a model space rather than individual performance of each model. Tuning parameters in the DI control the size of the model space for MA.     

Stop the Beat: Quiet Regulation and Cultural Conflict1

This article explores a recent conflict over the youth phenomenon known as “raving” in the City of Chicago. By interviewing participants involved in the conflict, I set out to understand the extent to which the crackdown on raves in Chicago was similar to earlier social reactions to jazz, comic books, rock and roll, and Dead Head culture, as well as to more recent conflicts over punk, rap music, and raves in other cities. While most previous research on cultural conflict has focused on moral crusades, campaigns, and panics, the Chicago conflict represents an example of “quiet regulation.” Opponents refrained from highly visible, morally charged attacks; instead, in the absence of media hype and visible public discourse, public officials justified the crackdown in highly bureaucratic terms—avoiding risk, collecting taxes, enforcing codes. Nonetheless, they also drew on cultural schemas that linked raves and raving with drugs, sex, and deviance. As a result, officials selected a course of regulation that criminalized DJs and discredited the artform. In the absence of a highly visible moral campaign, the rave participants were unable to mobilize and resist the regulation and defend their lifestyle. Sociologists must move beyond highly visible campaigns and crusades and pay greater attention to quiet regulation, both because such regulation is likely to increase in the future and because it has significant consequences for power, cultural expression, and identity.     

Neo‐liberalism by Decay? The Evolution of the Czech Welfare State

In this article we analyse the evolution of the Czech welfare state and we examine the factors explaining its path. We show that although the Czech welfare regime exhibits a 'mixed profile' that includes conservative and universalist elements, it is increasingly moving in a more liberal, residualist direction – not because of conscious steps but rather through decay. Governments have often zig-zagged in their policies and resorted to symbolic reforms at times rather than implementing ideologically based, consistent policies. We argue that historical and sociological institutionalism combined with a social-capital approach can explain this decay better than the more common arguments about economic pressures combined with ideological hegemony or the protest-avoidance strategy. In particular, the social capital approach adds to our institutional framework by explaining why cutbacks in welfare programmes have not met much opposition, even though public opinion surveys consistently show support for more generous welfare policies, and why policies have deviated so much from political rhetoric.