On the computation of the noncentral <Emphasis Type="Italic">F</Emphasis> and noncentral beta distribution

Unfortunately many of the numerous algorithms for computing the comulative distribution function (cdf) and noncentrality parameter of the noncentral F and beta distributions can produce completely incorrect results as demonstrated in the paper by examples. Existing algorithms are scrutinized and those parts that involve numerical difficulties are identified. As a result, a pseudo code is presented in which all the known numerical problems are resolved. This pseudo code can be easily implemented in programming language C or FORTRAN without understanding the complicated mathematical background. Symbolic evaluation of a finite and closed formula is proposed to compute exact cdf values. This approach makes it possible to check quickly and reliably the values returned by professional statistical packages over an extraordinarily wide parameter range without any programming knowledge. This research was motivated by the fact that a very useful table for calculating the size of detectable effects for ANOVA tables contains suspect values in the region of large noncentrality parameter values compared to the values obtained by Patnaik’s 2-moment central-F approximation. The cause is identified and the corrected form of the table for ANOVA purposes is given. The accuracy of the approximations to the noncentral-F distribution is also discussed. The authors wish to thank Mr. Richárd Király for his preliminary work. The authors are grateful to the Editor and Associate Editor of STCO and the unknown reviewers for their helpful suggestions.     

The U.S. Health System and Immigration: An Institutional Interpretation1

We examine the institutions that comprise the U.S. health system and their relationship to a surging immigrant population. The clash between the system and this human flow originates in the large number of immigrants who are unauthorized, poor, and uninsured and, hence, unable to access a system largely based on ability to pay. Basic concepts from sociological theory are brought to bear on the analysis of this clash and its consequences. Data from a recently completed study of health institutions in three areas of the United States are used as an empirical basis to illustrate various aspects of this complex relation. Implications of our results for theory and future health policy are discussed.     

Getting to know reality and breaking stereotypes: the experience of two generations of working disabled women

This paper sets out the results of a Spanish study of the experience and meaning of work among disabled women of two generations, with three types of disability (physical, visual and hearing). Performing a socially recognised activity such as a job is a source of emotional welfare and self‐esteem. Moreover, it confers a certain social status. For the participants in this study the kind of work involved, whether productive, paid and ‘extra‐domestic’ or ‘reproductive’, unpaid and done at home, acquires different meanings, since for disabled women, sexist stereotypes – already more or less accentuated in the culture – social attitudes towards disability and personal factors introduce relevant differences, while leading to conflicts and dilemmas that these women have to solve. At any rate, their sense of responsibility in performing all types of work should be emphasised as evidence of their sense of independence and personal competence, forming a keystone in their construction of a sense of identity and social integration.     

Nonlinear models of disability and age applied to census data

It is usually considered that the proportion of handicapped people grows with age. Namely, the older the man/woman, the more the level of disability he/she suffers. However, empirical evidence shows that this assessment is not always true, or at least, it is not true in the Spanish population. The study tries to assess the impact of age on disability in Spain. Each gender has been treated separately because it can be shown that men and women have their own pattern of behaviour. Three different methods of estimation have been used to check the link between those variables. The results seem to support the idea that the relationship among age and the intensity of disability is not always direct. One of the concluding remarks in this analysis is that the method of estimation has a great incidence in the final results, especially in central ages between 20 and 80 years old.     

Factors Preventing Gridlock in Chilean Couples’ Relationships Based on the Discourse of Couples Therapists and Highly Adjusted Couples

The term gridlock describes the occurrence of rigid patterns in couples’ conflict. This study aimed to describe strategies of conflict resolution and gridlock prevention from the perspectives of couples and couple therapists. Participants were couple therapists and highly adjusted couples scored by the dyadic adjustment scale (DAS), distributed according to traditional and non‐traditional position in life and duration of relationships. Conflict gridlock scenarios were used to create video stimulus that were presented to participants. A qualitative methodology was used to analyse couples’ and therapists’ commentaries on the scenarios. Results showed differences in preventing conflict gridlock among sub‐groups of couples. Long‐term traditional couples focused on loyalty to a common project and value sacrificing to a higher good; long‐term non‐traditional couples prioritised caring and validating the bond in the relationship. Short‐term traditional couples focused on mutual love and the relief of hurt while short‐term non‐traditional couples supported the value of equity.     

Analysis of the non-native flora of Ensenada, a fast growing city in northwestern Baja California

Urbanized areas show a high proportion of non-native plants and can work as dispersal points to the surrounding areas. Ensenada is a fast growing city located in the northwestern peninsula of Baja California (Mexico). It is the southern extreme of a bi-national, coastal urban corridor that extends from Los Angeles, California south to Ensenada. This corridor is part of the biodiversity hotspot of the California Floristic Province. The aim of this study was to analyze the composition and distribution of the spontaneous flora in the city of Ensenada. We systematically sampled two differentiated urban environments, vacant lots and arroyos, in 2006 and 2007. We found a total of 158 plant species, 61% of them were non-native species. Arroyo areas showed higher non-native species richness than vacant lots (21.9 vs. 13.6 species/transect) and could be potential dispersal vectors for non-native species to natural areas outside of the city, or in the reverse direction also.     

Accuracy of approximate progressively censored reliability sampling plans for exponential models

Reliability sampling plans provide an efficient method to determine the acceptability of a product based upon the lifelengths of some test units. Usually, they depend on the producer and consumer’s quality requirements and do not admit closed form solutions. Acceptance sampling plans for one- and two-parameter exponential lifetime models, derived by approximating the operating characteristic curve, are presented in this paper. The accuracy of these approximate plans, which are explicitly expressible and valid for failure and progressive censoring, is assessed. The approximation proposed in the one-parameter case is found to be practically exact. Explicit lower and upper bounds on the smallest sample size are given in the two-parameter case. Some additional advantages are also pointed out.     

Working mothers’ decisions on childcare: the case of Spain

This paper aims to analyze household decisions regarding the childcare of young children. We present two specifications. The first one assumes a sequential decision process. Firstly, parents choose between paid or unpaid care and, secondly, those who opt for paid childcare must decide whether to take their children to a nursery or pre-school or employ somebody to care for them. The second specification is a multinomial Logit in which it is assumed that parents choose from three alternatives: unpaid care, paid care by a nanny, and center-based care. We apply our models to a sample of working mothers with children under three. The database used is the 2008–2010 Spanish Survey of Quality of Working Life (Encuesta de Calidad de Vida en el Trabajo). The results are in line with previous work: Parental education, family composition, income and the characteristics of the mother’s job are important factors in determining the type of childcare chosen for under-three-year-olds.