An exact two-sample test based on the baumgartner-weiss-schindler statistic and a modification of lepage's test

It is shown that the nonparametric two-saniDle test recently proposed by Baumgartner, WeiB, Schindler (1998, Biometrics, 54, 1129-1135) does not control the type I error rate in case of small sample sizes. We investigate the exact permutation test based on their statistic and demonstrate that this test is almost not conservative. Comparing exact tests, the procedure based on the new statistic has a less conservative size and is, according to simulation results, more powerful than the often employed Wilcoxon test. Furthermore, the new test is also powerful with regard to less restrictive settings than the location-shift model. For example, the test can detect location-scale alternatives. Therefore, we use the test to create a powerful modification of the nonparametric location-scale test according to Lepage (1971, Biometrika, 58, 213-217). Selected critical values for the proposed tests are given.     

A robust modification of the ordered-heterogeneity test

An ordered heterogeneity (OH) test is a test for a trend that combines a non-directional heterogeneity test with the rank-order information specified under the alternative. We propose two modifications of the OH test procedure: (1) to use the mean ranks of the groups rather than the sample means to determine the observed ordering of the groups, and (2) to use the maximum correlation out of the 2^k???1 – 1 possibilities under the alternative rather than the single ordering (1, 2, … , k), where k is the number of independent groups. A simulation study indicates that these two changes increase the power of the ordered heterogeneity test when, as common in practice, the underlying distribution may deviate from a normal distribution and the trend pattern is a priori unknown. In contrast to the original OH test, the modified OH test can detect all possible patterns under the alternative with a relatively high power.     

Protecting the Old in a Young Economy: Old Age Insurance in the West Bank and Gaza Strip

Taking the West Bank and Gaza Strip as a reference point, this paper looks at social protection in developing economies, which are beset by economic stagnation, widespread poverty and unemployment. If the main breadwinner dies, is unable to work or is an older person, these factors are prime causes of absolute poverty. This is hardly surprising, since private and public systems of social security are totally inadequate in this area in particular. Current thinking on social security suggests that what is needed is the rapid introduction of a comprehensive system of retirement provision, comprising a mandatory capital-funded insurance component, with defined contributions, administered on a decentralized basis; and a state-administered pay-as-you-go basic insurance component with lump-sum transfers to safeguard the poorest. A system of this kind works to prevent poverty in old age by redistributing funds from some individuals to others and ensuring an income for life, and it represents a compromise between a fair return on what people have contributed and a fair distribution over society as a whole. It is thus a major force for stability in society.     

Individual Differences in Infant Skills as Predictors of Child-Caregiver Joint Attention and Language

Current research suggests that the extent to which child-caregiver dyads engage in interactions involving episodes of joint or coordinated attention can have a significant impact on early lexical acquisition. In this regard it has been recognized that individual differences in early developing child communication skills, such as capacity to follow gaze and early infant language, may contribute to these child-caregiver interactional patterns, as well as to subsequent language development. To address this expectation, 21 infant-parent dyads were recruited for participation in a longitudinal study. Early infant language, responding to joint attention skill, and cognitive development were assessed at 12 months of age. Child-caregiver joint attention episodes, as well as responding to joint attention skill and child language, were assessed at 18 months of age. Developmental outcome, using the MacArthur Communicative Development Inventories and the Bayley Scales of Infant Development-II, was assessed at 21 and 24 months of age. Consistent with previous findings, results indicated that individual differences in child-caregiver episodes of joint attention were related to language at 18 months. In addition, though, 12 month vocabulary and responding to joint attention skill were associated with some aspects of 18 month child-caregiver interaction, as well as subsequent language development. In general, 12 month child measures and 18 month child-caregiver interaction measures appeared to make unique contributions to language development in this sample. These results suggest the need to further consider the role of infant skills in the connections between child-caregiver joint attention episodes and language development.     

Legal problems of health care cost containment.

Employers faced with rising health care costs are exploring various means to control them. One way is prospective utilization review, although this may pose significant legal risks. Another is the capitation form of payment in which an employer contracts with a health care provider either directly or through an employer-sponsored HMO. The authors discuss these alternatives and the implications for employers.     

Maximum Test versus Adaptive Tests for the Two-Sample Location Problem

For the non-parametric two-sample location problem, adaptive tests based on a selector statistic are compared with a maximum and a sum test, respectively. When the class of all continuous distributions is not restricted, the sum test is not a robust test, i.e. it does not have a relatively high power across the different possible distributions. However, according to our simulation results, the adaptive tests as well as the maximum test are robust. For a small sample size, the maximum test is preferable, whereas for a large sample size the comparison between the adaptive tests and the maximum test does not show a clear winner. Consequently, one may argue in favour of the maximum test since it is a useful test for all sample sizes. Furthermore, it does not need a selector and the specification of which test is to be performed for which values of the selector. When the family of possible distributions is restricted, the maximin efficiency robust test may be a further robust alternative. However, for the family of t distributions this test is not as powerful as the corresponding maximum test.     

Unconditional Quantile Treatment Effects Under Endogeneity

This article develops estimators for unconditional quantile treatment effects when the treatment selection is endogenous. We use an instrumental variable (IV) to solve for the endogeneity of the binary treatment variable. Identification is based on a monotonicity assumption in the treatment choice equation and is achieved without any functional form restriction. We propose a weighting estimator that is extremely simple to implement. This estimator is root n consistent, asymptotically normally distributed, and its variance attains the semiparametric efficiency bound. We also show that including covariates in the estimation is not only necessary for consistency when the IV is itself confounded but also for efficiency when the instrument is valid unconditionally. An application of the suggested methods to the effects of fertility on the family income distribution illustrates their usefulness. Supplementary materials for this article are available online.     

Organisationsentwicklung und Organisationsberatung im Zeichen reflexiver Modernisierung

The theory and practice of Organizational Development and Consulting are in a phase of transition from classic to reflexive modernization. While the readiness to not perform the modernization of organisations according to classic rational models is growing, conflicting expectations ensure their persistant use in practice. Using various research concerning the transformation process in Eastern Germany it is shown that this phase did not create a break with the classic rational model of organization. The theory of Organizational Development and Consulting needs to reflect on this and other problems of the transitional phase and itself become more reflective on the relationsship of the theory and practice of organizational development.     

Wirkungen des TV-Duells im Vorfeld der Bundestagswahl 2005 auf die Wahlentscheidung

During the election campaign to the German Federal Election 2005 the incumbent chancellor Gerhard Schröder and his challenger Angela Merkel met one another on the occasion of a televised debate, the so-called “TV-duel”. This debate was viewed by roughly one third of the German electorate. It is analyzed, whether the perception of the TV-duel winner has had an influence on the voting decision. In the empirical analyses special regard is given to the stability of the winner perception until election day and the influence of subjective expectations towards the debate performance of the candidates. The data analyzed were collected by means of a new interviewing technology via the television screen of the respondents. It is shown, that the winner perception was largely stable and only marginally influenced by the media coverage following the debate. Subjective expectations towards the debate performance of the candidates turn out to be of no importance for the voting decision. The effect of the winner perception on voting behaviour was mediated by changing candidate orientations.     

Item nonresponse on income questions in panel surveys: Incidence, imputation and the impact on inequality and mobility

Summary: This paper deals with item nonresponse on income questions in panel surveys and with longitudinal and cross–sectional imputation strategies to cope with this phenomenon. Using data from the German SOEP, we compare income inequality and mobility indicators based only on truly observed information to those derived from observed and imputed observations. First, we find a positive correlation between inequality and imputation. Secondly, income mobility appears to be significantly understated using observed information only. Finally, longitudinal analyses provide evidence for a positive inter–temporal correlation between item nonresponse and any kind of subsequent nonresponse.* We are grateful to two anonymous referees and to Jan Goebel for very helpful comments and suggestions on an earlier draft of this paper. The paper also benefited from discussions with seminar participants at the Workshop on Item Nonresponse and Data Quality in Large Social Surveys, Basel/CH, October 9–11, 2003.