On locally optimal invariant unbiased tests for the variance components ratio in mixed linear models

In the paper the problem of testing of two-sided hypotheses for variance components in mixed linear models is considered. When the uniformly most powerful invariant test does not exist (see e.g. Das and Sinha, in Proceedings of the second international Tampere conference in statistics, 1987; Gnot and Michalski, in Statistics 25:213–223, 1994; Michalski and Zmyślony, in Statistics 27:297–310, 1996) then to conduct the optimal statistical inference on model parameters a construction of a test with locally best properties is desirable, cf. Michalski (in Tatra Mountains Mathematical Publications 26:1–21, 2003). The main goal of this article is the construction of the locally best invariant unbiased test for a single variance component (or for a ratio of variance components). The result has been obtained utilizing Andersson’s and Wijsman’s approach connected with a representation of density function of maximal invariant (Andersson, in Ann Stat 10:955–961, 1982; Wijsman, in Proceedings of fifth Berk Symp Math Statist Prob 1:389–400, 1967; Wijsman, in Sankhyā A 48:1–42, 1986; Khuri et al., in Statistical tests for mixed linear models, 1998) and from generalized Neyman–Pearson Lemma (Dantzig and Wald, in Ann Math Stat 22:87–93, 1951; Rao, in Linear statistical inference and its applications, 1973). One selected real example of an unbalanced mixed linear model is given, for which the power functions of the LBIU test and Wald’s test (the F-test in ANOVA model) are computed, and compared with the attainable upper bound of power obtained by using Neyman–Pearson Lemma.     

Estimation of a relative potency of two preparations with correlated responses

Estimation of a relative potency of two preparations in so-called parallel-line assays is presented. A special type of incomplete Latin square designs where doses of preparations are administered is considered. Testing hypotheses about similarity of preparations and their relative potency in the case of correlated observations are regarded. Confidence interval for the relative potency of preparations is also given. Theoretical considerations are applied to point and interval estimation of potencies of new tuberculins with respect to some international standards tested in experiments on guinea-pigs.     

Double ASN Minimax sampling plans by variables when the standard deviation is unknown

We deal with the double sampling plans by variables proposed by Bowker and Goode (Sampling Inspection by Variables, McGraw–Hill, New York, 1952) when the standard deviation is unknown. Using the procedure for the calculation of the OC given by Krumbholz and Rohr (Allg. Stat. Arch. 90:233–251, 2006), we present an optimization algorithm allowing to determine the ASN Minimax plan. This plan, among all double plans satisfying the classical two-point-condition on the OC, has the minimal ASN maximum.     

Use It or Save It? Migration Background and Parental Leave Uptake in Sweden

Sweden is a welfare state with a family policy that strongly emphasizes equality without distinction by place of birth or gender. In this study, we investigate the differences in uptake of parental leave between native and immigrant mothers, and the connection to labour-market attachment. Sweden represents a unique case study, not only because of the strong effort to combine work and family for all women and men, the high level of fertility and the large presence of immigrants in the country; it also enables a detailed and sophisticated analysis based on the high-quality data derived from its population registers. We find that immigrant mothers use more parental leave benefit the first year after their child’s birth, but then fewer in the second year compared with native mothers. The differences diminish when labour-market activity is controlled for. Additionally, after a time in Sweden, immigrant mothers use leave more similarly to how native mothers do.     

Intersection of Ethnicity,Gender and Class: Oriental Faculty Women in Israel

Ethnicity, gender and class are the major factors of social inequality and have been studied extensively leading to a large literature pertaining to each one of them. The issue of the intersection of ethnicity, gender and class has been introduced into the social sciences by feminist critical theory. Intersection theory postulates that minority groups are discriminated against on the basis of more than one characteristic which are “inextricably tied” leading to complex forms of inequality in various social domains. This study examines the intertwined effects of these factors as they are experienced and narrated by Mizrachi women (19) who are employed in universities and colleges. Although the intersection approach is generally supported by the data it was found that under certain conditions ethnicity, gender and class may be separated. One type of decomposition is when one identity encroaches upon another or others; the second is the separation of diverse identities assigning them to different life areas. These change processes do not support stereotypical dichotomies between Ashkenazi and Mizrachi, women and men and so on, and enable the creation of new hybrid identities.