bluuebunny/crossref_metadata_2025 huggingface dataset:
The Assessment of Peer Selection and Peer Environmental Influences on Behavior Using Pairs of Siblings or Twins
Authors: Madden Pamela A. F. , Bucholz Kathleen K. , Todorov Alexandre A. , Grant Julia D. , Heath Andrew C.
Published: May 2007

Many studies have found strong peer correlations for a variety of problem behaviors that begin in adolescence (e.g. substance use). Such correlations are commonly attributed to peer influences, but could also be explained by selective (‘assortative’) friendship: the tendency for those with similar patterns of behavior to become friends. Here we show how, under certain assumptions, cross-sectional data from pairs of siblings or twins and their peers may be used to resolve the contributions of peer selection and reciprocal peer environmental influences to peer resemblance. We performed power calculations to determine necessary sample sizes for rejecting with 80% power, at the 5% significance level, the hypothesis of only peer selection effects, or only reciprocal peer environmental effects. A false hypothesis of only selective friendship effects was always easier to reject than a false hypothesis of only reciprocal peer environmental influences. Limitations of these simulations, including uncertainty about the most appropriate way to model peer selection, are discussed.
Why do Identical Twins Differ in Personality: Shared Environment Reconsidered
Authors: Torgersen Anne Mari , Janson Harald
Published: May 2007

While heritability studies show that most of the variance in adult personality can be attributed to genetic or so-called nonshared environmental influence, this does not mean that shared events lack importance for the development of later personality differences. We studied the relationship between Big Five personality differences in monozygotic (MZ) twins at age 29, and life stressors at age 6 to 15, using prospective data from 26 MZ pairs studied from birth onwards. A positive significant correlation was found between stressors in childhood and early adolescence, and intrapair personality differences in Agreeableness, Openness, Conscientiousness, and five-factor profiles. We note that the effects of shared events are labeled “nonshared” environment when the effect is to make siblings more different. Case examples illustrate the relationship between stress and personality differences, and provide hypotheses for further studies in larger samples.
Rejoinder to Meta-Analysis of Twin-Twin Transfusion by Skupski et al.
Authors: Machin Geoffrey A.
Published: May 2007

Assessment of treatment options in twin-twin transfusion should involve a detailed interrogation of the placenta and fetuses prior to treatment, stratification according to response to amnioreduction and careful analysis of quality of survival. Amnioreduction and laser coagulation are not alternative and equivalent modalities for the treatment of twin-twin transfusion. Randomized trials may not be ethical without prior therapeutic/ diagnostic amnioreduction.
Hypertensive Disease in Twin Pregnancies: A Review
Authors: Krotz Stephan , Fajardo Javier , Ghandi Sanjay , Patel Ashlesha , Keith Louis G.
Published: May 2007

Reports over the past seventy years show that twin gestations lead to an increased risk of hypertensive disorders. Numerous studies discuss the incidence of hypertensive disease in twin versus singleton gestations, as well as effects of parity, race, age, income level, smoking, zygosity and heritability on this condition. The range of relative risk of gestational hypertension, preeclampsia and eclampsia for twin compared to singleton gestations is 1.2 to 2.7, 2.8 to 4.4 and 3.4 to 5.1 respectively. Parity, African-American ethnicity, and young maternal age are all factors that increase the relative risk of acquiring hypertensive disease to 4.0, 1.8 and 1.5 in mothers of twin gestations. Factors such as maternal smoking, income level and zygosity have a negligible effect on the relative risk of acquiring hypertensive disease in twin gestations. In addition to twin mothers exhibiting a higher incidence of hypertensive disease compared to their singleton counterparts, they also exhibit an earlier onset of hypertensive disease at both 35 and 37 weeks of gestation comparatively. Uric acid levels measured at 30–31 weeks of gestation in twin mothers predicted the onset of preeclampsia with a sensitivity of 73% and a specificity of 74%. The range of risks presented in the literature is wide and the therapies avocated are diverse. We therefore decided to summarize the risks in a comparative fashion and to review current therapeutic strategies for the convenience of clinicians who confront increasing numbers of multiple pregnancies. The tables bring all recent published risks together in the first comparative analysis in which the data has been converted to relative risks and confidence intervals. Because the literature is relatively silent on specific management of hypertensive disease in twin pregnancies, general management recommendations for singleton gestations should be used by practitioners caring over twin gestations.
Perinatal Mortality in Term and Preterm Twin and Singleton Births
Authors: Payne Jennifer C. , Campbell M. Karen , DaSilva Orlando , Koval John
Published: May 2007

Although, in general, twins have higher perinatal mortality rates than singletons, preterm twins have lower perinatal mortality rates than singletons of the same birth weight or gestational age. This study investigated the hypotheses that this paradoxical twin advantage: 1) is due to gestational age distribution differences between the singleton and twin populations, and 2) is due to increased likelihood of birth having occurred in a tertiary perinatal center. A pre-existing, time-limited data set of all births in the province of Ontario in odd years between 1979 and 1985 was chosen for this study because of the large sample size (n = 618,579). Multivariable logistic regression of the relationship between perinatal mortality and twin status was controlled for mother’s age, hospital level and gestational age. Findings confirm the lower mortality of preterm twins. After controlling for level of hospital of birth this difference remained, suggesting that level of hospital of birth was not a major factor responsible for the twin advantage. Analyses in which gestational age was standardized indicate that, for those whose gestational age was less than 2 SD below the mean for their particular group (twin or singleton), twins were actually at higher risk than singletons. These results support hypothesis 1 and do not strongly support hypothesis 2. The results also support earlier authors’ suggestions that the definition of term birth should be different for twins and singletons
A Comparison of Educational Achievement in a National Sample of Dutch Female Twins and Their Matched Singleton Controls
Authors: Cohen Celina C.C. , van Goozen Stephanie H. M. , Orlebeke Jacob F. , Buitelaar Jan K. , Cohen-Kettenis Peggy T.
Published: May 2007

The aim of this study was to compare the educational achievement of female twins (n = 577) and their matched singleton controls (n = 447), who were selected from participants of a national test of educational achievement in the years 1993 to 1998. To assure the representativeness of the selected groups we also compared the achievement scores of the twins and the controls to those of the total Dutch female population tested in the same period. We analyzed the results of the following educational achievement scales: Language, Mathematics and Information Processing. The results indicated that the singleton classmates performed significantly better than the twins on all three scales. However, the twins performed equally well as compared to the Dutch female population. We believe that our singleton control group was not as properly selected as we intended, a selection bias operative at the level of the schools may have confounded the comparison. We therefore conclude on the basis of a comparison with the performance of the total Dutch female population that there are no differences in educational achievement between female twins and singletons.
Genetic and Environmental Influences on Expression of Recurrent Headache as a Function of the Reporting Age in Twins
Authors: Svensson Dan A. , Larsson Bo , Waldenlind Elisabet , Pedersen Nancy L.
Published: May 2007

To explore age-related mechanisms in the expression of recurrent headache, we evaluated whether genetic and environmental influences are a function of the reporting age using questionnaire information that was gathered in 1973 for 15- to 47-year-old Swedish twins (n =12,606 twin pairs). Liability to mixed headache (mild migraine and tension-type headache) was explained by non-additive genetic influences (49%) in men aged from 15 to 30 years and additive genetic plus shared environmental influences (28%) in men aged from 31 to 47 years. In women, the explained proportion of variance, which was mainly due to additive genetic effects, ranged from 61% in adolescent twins to 12% in twins aged from 41 to 47 years, whereas individual specific environmental variance was significantly lower in twins aged from 15 to 20 years than in twins aged from 21 to 30 years. Liability to migrainous headache (more severe migraine) was explained by non-addi-tive genetic influences in men, 32% in young men and 45% in old men, while total phenotypic variance was significantly lower in young men than in old men. In women, the explained proportion of variance ranged from 91% in the youngest age group to 37% in the oldest age group, with major contributions from non-additive effects in young and old women (15–20 years and 41–47 years, respectively) and additive genetic effects in intermediate age groups (21–40 years). While total variance showed a positive age trend, genetic variance tended to be stable across age groups, whereas individual specific environmental variance was significantly lower in adolescent women as compared to older women.
HLA Haplotypes in Dizygotic Twin Pairs: Are Dizygotic Twins More Similar Than Sibs?
Authors: Titlestad Ingrid Louise , Kyvik Kirsten Ohm , Kristensen Tom , Lillevang Søren
Published: May 2007

It has been suggested that dizygotic twin pairs share two HLA haplotypes more often than ordinary siblings and thus might be genetically more alike. We tested this hypothesis in dizygotic twin pairs from the Danish Twin Registry. A total of 114 (60 female and 54 male) same-sexed healthy twin pairs aged 18–45 years participated. Dizygosity was established by means of DNA sequencing of nine polymorphic markers. HLA-A, B and Cw specificities were typed with serology, and if data were inconclusive, with DNA typing. If twin partners had the same HLA-types, they were assumed to share two haplotypes. If they had 1 HLA A, B and C antigen group in common they were assumed to share one haplotype and if they had no HLA types in common they were assumed to share zero haplotypes. Since HLA-types from parents were unavailable we could not test for identity-by-descent and thus had a risk of overestimating the number of twins sharing two haplotypes. A Chi-square test was used to compare observed numbers in each haplotype sharing group with the expected numbers. Twenty-nine (expected 28.5) twin pairs had two HLA-types in common, 52 (expected 57) had one HLA-type in common and 33 (expected 28.5) had zero HLA-types in common, p = 0.56. Our data show that DZ twins are not more similar than sibs from different pregnancies in general.
Analysis of Functional Abilities for Elderly Danish Twins Using GEE Models
Authors: Iachina Maria , Jørgensen Bent , Christensen Kaare , Iachine Ivan
Published: May 2007

In this work we present a new method for genetic analysis of twin data which is based on generalized estimating equations and allows for analysis of various response types (e.g., continuous, binary, counts) combined with estimation of residual correlations. The new approach allows for control of covariates of any kind (e.g., continuous, counts) by modeling the dependence of mean and variance on background variables. The proposed method was applied to identify the covariates that have a significant influence on elderly people’s functional abilities, and find the estimates for the correlation coefficients of residuals for MZ and DZ twins in a sample of 2401 Danish twin 75 years of age or older. The bootstrap method was used to obtain standard errors for correlation coefficients. It was shown, that the chosen covariates have similar effects on MZ and DZ twins, and that the residual correlation in MZ twins is significantly higher than in DZ twins, which indicates that genetic factors play an etiological role in the determination of physical status of elderly people, controlled for 10 background variables.
Paternally Derived Twinning: A Two Century Examination of Records of One Scottish Name
Authors: St Clair John B. , Golubovsky Mikhail D.
Published: May 2007

Paternal influence on twinning was investigated through a study of all the state and church records of Scotland for the period 1800–2000 (nine generations) in relation to one Scottish patronymic — in total 50,000 births. All recorded twins born with the chosen patronymic were identified and their whole paternal ascent and descent on the male line were charted for twins. There were established three pedigrees A, B and C manifesting clear paternal twinning hereditary transmission. Detailed familial reproduction patterns were traced for pedigree A, including phenotypic identification of twin zygosity in relation to seven same sexed pairs of twins in the pedigree and one same sexed pair out of dizygotic triplets. It is the most comprehensive description to date of such a kind of twin familial trait. The data presented show (i) the unique feature of clear direct paternal influence on twinning in three families; (ii) paternal factor(s) determination in both DZ and MZ twinning; and (iii) a definite association of twinning tendency with a partial male infertility, which corresponds to the prediction of the Infertility/Twinning Paternally Dependent syndrome hypothesis. The hypothesis of a founder effect explaining the similarity of A, B, C families and the possible localisation of the paternally dependent twinning factor on the Y-chromosome are currently under molecular investigation.
The Case for the Odd Case, Research Reviews, Parenting Pandas
Authors: Segal Nancy L.
Published: May 2007

Many twin researchers occasionally encounter twin pairs displaying unusual physical, medical or behavioral traits. Unfortunately, these interesting cases are often unreported because they do not fit in easily with ongoing projects. However, these “odd cases” may suggest new hypotheses, new designs or entirely new projects. In this paper, I argue in favor of publishing case studies of exceptional twins, and refer to several large scale studies inspired by such reports. Several informative case studies are then summarized: DZ twins discordant for hyperinsulinism, DZ twins born after ICSI, “simultaneous madness in twins, and sixteenth century conjoined twins. The article concludes with a review of parenting twin pandas.
Osteoarthritis of the Hands, Hips and Knees in an Australian Twin Sample — Evidence of Association with the Aggrecan VNTR Polymorphism
Authors: Kirk Katherine M. , Doege Kurt J. , Hecht Jacqueline , Bellamy Nicholas , Martin Nicholas G.
Published: May 2007

Age-related changes in the composition of the cartilage matrix may be associated with the development of osteoarthritis, a relatively late-onset disease characterised by the destruction of joint cartilage. In order to investigate whether differences in the VNTR polymorphic region of aggrecan affect cartilage functionality and therefore the development of osteoarthritis, we examined the aggrecan polymorphic genotypes of a sample of 134 Australian twins aged over 50 (including 34 monozygotic and 27 dizygotic twin pairs). Clinical measures of hand, hip and knee osteoarthritis, as well as self-reported bone and joint pain, were tested for association with the aggrecan polymorphism. The results were consistent with either a deleterious effect of allele 27, or a protective effect of alleles 25 and 28, providing some additional evidence for an association between the aggrecan VNTR polymorphism and osteoarthritis of the hands, hips and knees.
Comparison of Child-rearing Problems Between Mothers with Multiple Children who Conceived after Infertility Treatment and Mothers with Multiple Children who Conceived Spontaneously
Authors: Yokoyama Yoshie
Published: May 2007

The purpose of this study was to clarify the characteristic child-rearing problems for mothers of multiple children who conceived after infertility treatment as compared to mothers of multiple children who conceived spontaneously. The subjects were 990 mothers of multiple children: 359 who conceived after infertility treatment and 631 who conceived spontaneously. Mothers who conceived after infertility treatment were more delighted when informed of a multiple pregnancy than those who conceived spontaneously. In addition, with respect to anxiety during twin pregnancies, mothers of twins who conceived after infertility treatment showed lower rates of anxiety about nursing the infants and economic concerns than those of twins who conceived spontaneously. However, after delivery, mothers who conceived after infertility treatment showed a higher rate of depressive symptoms than those who conceived spontaneously. After adjusting for each associated factor using logistic regression, the risk of depressive symptoms in mothers who conceived after infertility treatment was significantly associated with disabled multiple children and the methods for alleviating stress. The odds ratio indicated that mothers with at least one disabled child were twice as likely to have depressive symptoms as mothers with no disabled children. Furthermore, the odds ratio indicated that mothers who used no methods for alleviating stress were twice as likely to have depressive symptoms than those who did.
In Detail; Research Reviews; Of New Interest
Authors: Segal Nancy L.
Published: May 2007

Two families with twins — one in which adult DZ twins continue to face the risk of frontotemporal dementia, and the other in which a mother copes with brittle bones in a newborn infant MZ pair — are featured. The nature and progress of the disorders are reviewed and personal perspectives from the twins and other family members are variously provided. Next, four current twin studies are briefly summarized. Topics include sex differences in social support systems, new reproductive technologies, comparative twin-singleton frequencies of placenta previa, and the nature and complications of heterotopic pregnancies. This article concludes with a brief sampling of human interest stories involving twins: a different looking DZ pair, newborn sextuplets, conjoined twins and opposite-sex twin athletes.
Quantitative Association Tests of Immune Responses to Antigens ofMycobacterium Tuberculosis: A Study of Twins in West Africa
Authors: Wiart Amanda , Jepson Annette , Banya Winston , Bennett Steve , Whittle Hilton , Martin Nicholas G. , Hill Adrian V. S.
Published: May 2007

There is now considerable evidence that host genetic factors are important in determining the outcome of infection withMycobacterium tuberculosis(MTB). The aim of this study was to assess the role of several candidate genes in the variation observed in the immune responses to MTB antigens. In-vitro assays of T-cell proliferation, an in-vivo intradermal delayed hypersensitivity response; cytokine and antibody secretions to several mycobacterial peptide antigens were assessed in healthy, but exposed, West African twins. Candidate gene polymorphisms were typed in theNRAMP1,Vitamin D receptor,IL10,IL4,IL4 receptorandCTLA-4genes. Variants of the lociIL10(−1082 G/A),CTLA-4(49 A/G) and theIL4 receptor(128 A/G) showed significant associations with immune responses to several antigens. T-cell proliferative responses and antibody responses were reduced, TNF-α responses were increased for subjects with theCTLA-4G allele. The T-cell proliferative responses of subjects withIL10GA and GG genotypes differed significantly.IL4 receptorAG and GG genotypes also showed significant differences in their T-cell proliferative responses to MTB antigens. These results yield a greater understanding of the genetic mechanisms that underlie the immune responses in tuberculosis and have implications for the design of therapeutic interventions.
Genetic Influences on Female Infidelity and Number of Sexual Partners in Humans: A Linkage and Association Study of the Role of the Vasopressin Receptor Gene (AVPR1A)
Authors: Cherkas Lynn F. , Oelsner Elizabeth C. , Mak Y. T. , Valdes Anna , Spector Tim D.
Published: May 2007

In humans, in contrast to animals, the genetic influences on infidelity are unclear. We report here a large study of over 1600 unselected United Kingdom female twin pairs who confidentially reported previous episodes of infidelity and total lifetime number of sexual partners, as well as attitudes towards infidelity. Our findings demonstrate that infidelity and number of sexual partners are both under moderate genetic influence (41% and 38% heritable, respectively) and the genetic correlation between these two traits is strong (47%). Conversely, attitudes towards infidelity are driven by shared and unique environmental, but not genetic, influences. A genome-wide linkage scan identified three suggestive but nonsignificant linkage areas associated with infidelity and number of sexual partners on chromosomes 3, 7 and 20 with a maximum LOD score of 2.46. We were unsuccessful in associating infidelity or number of sexual partners with a locus implicated in other mammals' sexual behavior, the vasopressin receptor gene. Nonetheless, our findings on the heritabil-ity of sexual infidelity and number of sexual partners provide support for certain evolutionary theories of human sexual behavior, as well as justifying further genetic and molecular research in this domain.
Linkage and Segregation Analysis of Black and Brindle Coat Color in Domestic Dogs
Authors: Kerns Julie A , Cargill Edward J , Clark Leigh Anne , Candille Sophie I , Berryere Tom G , Olivier Michael , Lust George , Todhunter Rory J , Schmutz Sheila M , Murphy Keith E , Barsh Gregory S
Published: May 2007

Mutations of pigment type switching have provided basic insight into melanocortin physiology and evolutionary adaptation. In all vertebrates that have been studied to date, two key genes, Agouti and Melanocortin 1 receptor (Mc1r), encode a ligand-receptor system that controls the switch between synthesis of red–yellow pheomelanin vs. black–brown eumelanin. However, in domestic dogs, historical studies based on pedigree and segregation analysis have suggested that the pigment type-switching system is more complicated and fundamentally different from other mammals. Using a genomewide linkage scan on a Labrador × greyhound cross segregating for black, yellow, and brindle coat colors, we demonstrate that pigment type switching is controlled by an additional gene, the K locus. Our results reveal three alleles with a dominance order of black (KB) > brindle (kbr) > yellow (ky), whose genetic map position on dog chromosome 16 is distinct from the predicted location of other pigmentation genes. Interaction studies reveal that Mc1r is epistatic to variation at Agouti or K and that the epistatic relationship between Agouti and K depends on the alleles being tested. These findings suggest a molecular model for a new component of the melanocortin signaling pathway and reveal how coat-color patterns and pigmentary diversity have been shaped by recent selection.
Imagining nation
Authors: Laungaramsri Pinkaew
Published: May 2007

This article explores the relationship between women, nation, nationalism, and transnational women’s practice through the Shan women’s movement in Thailand, particularly the international campaign to stop the systematic rape of Shan women by Burmese soldiers. Employing a feminist critique of nationalism, the article argues that transnational networks allow for the negotiation between national, local, and women’s identities. Whereas the authoritative power of nationalism continues to suppress and silence the transnational subjectivity of women, the Shan women’s movement represents a transnational attempt to contest the confinement of women’s subjectivities within the territorialized nation-state.
Film Review
Authors: Poblocki Kacper
Published: May 2007

John Marshall, A Kalahari family (five parts: “A
far country”—90 min., “End of the road”—60
min., “Real water”— 60 min., “Standing tall”—
60 min., and “Death by myth”—90 min.), 2003,
Documentary Educational Resources, Kalfam
Productions:Watertown MA.
An English/Spanish safety climate scale for construction workers
Authors: Jorgensen Emile , Sokas Rosemary K. , Nickels Leslie , Gao Weihua , Gittleman Janie L.
Published: May 2007

Background

Workers in the construction trades experience high rates of traumatic injury. An increasing number of workers in this industry speak only Spanish, including members of construction trade unions. This brief communication reports a dual language safety climate scale developed during a larger training intervention study.

Methods

Construction workers in two unions self‐completed a previously validated 6‐item safety climate scale modified for the construction trades. A seventh item was developed midway through the study and incorporated into the version completed by half of the respondents. For one union with a sizeable number of Spanish‐speaking members, a dual‐language (Spanish/English) version was administered. Follow‐up telephone interviews conducted 3 months after the self‐completed survey also included the safety climate scale.

Results

Cronbach's coefficient alpha was 0.85 for the 6‐item scale and 0.85 for the 7‐item scale. Similar coefficient alpha scores were found for the subgroup of Spanish‐speakers on the 6‐ and 7‐item scales. Spanish speakers with low education were less likely to respond to the scale when self‐completing but not when it was administered by telephone in Spanish.

Conclusion

This safety climate scale elicits consistent and reliable response from unionized construction workers when administered in English or in Spanish. Spanish literacy may be a consideration for the use of this scale among foreign‐born Hispanic workers. Am. J. Ind. Med. 50:438–442, 2007. © 2007 Wiley‐Liss, Inc.
Evidence for bronze age cannibalism in El Mirador Cave (Sierra de Atapuerca, Burgos, Spain)
Authors: Cáceres Isabel , Lozano Marina , Saladié Palmira
Published: May 2007

During excavations of the Bronze Age levels at El Mirador Cave, a hole containing human remains was found. Taphonomic analysis revealed the existence of cutmarks, human toothmarks, cooking damage, and deliberate breakage in most of the remains recovered, suggesting a clear case of gastronomic cannibalism. The piled distribution of the remains, the uneven skeletal representation, and the chronological difference between the pit and the remains suggest that these bones were subsequently buried by a human group that inhabited into the cave later in time. Evidence of gastronomic cannibalism has already been documented in Gran Dolina, another site in the Sierra de Atapuerca, on remains of Homo antecessor with an age of 800 ky (Fernández‐Jalvo et al.: Science 271 (1996) 277–278; Fernández‐Jalvo et al.: J Hum Evol 37 (1999) 591–622). Am J Phys Anthropol, 2007. © 2007 Wiley‐Liss, Inc.
Elektrophile Aktivierung von Alkenen mit Platin(II): sehr viel mehr als eine langsame Variante von Palladium(II)
Authors: Chianese Anthony R. , Lee Stephen J. , Gagné Michel R.
Published: May 2007

Die elektrophile Aktivierung von Alkenen durch Übergangsmetallkatalysatoren ist die erste Reaktionsstufe bei einer Vielzahl von katalytischen Prozessen. Das bekannteste Metall für diesen Zweck ist Palladium, in jüngerer Zeit konnten aber auch die besonderen Eigenschaften des verwandten Platins (starke Metall‐Ligand‐Bindungen, langsame Substitutionen) genutzt werden, um häufig komplementäre Umsetzungen zu entwickeln, die durch Addition von protischen Kohlenstoff‐, Stickstoff‐, Sauerstoff‐, Phosphor‐ sowie Alken‐ und Aren‐Nucleophilen an eine CC‐Bindung eingeleitet werden. Die Umsetzungen mit Platinreagentien zeigen oft sehr charakteristische Reaktivitätsprofile, die zu gänzlich neuen Reaktionsprodukten führen. Dieser Aufsatz gibt einen Überblick über Platin‐katalysierte elektrophile Aktivierungen von Alkenen, wobei die Beschreibung von Reaktionsmechanismen, die Unterschiede zwischen Platin‐ und Palladiumkatalysatoren und die Aussichten für die Entwicklung neuer Systeme im Mittelpunkt stehen.
Negative binomial version of the Lee–Carter model for mortality forecasting
Authors: Delwarde Antoine , Denuit Michel , Partrat Christian
Published: May 2007

Mortality improvements pose a challenge for the planning of public retirement systems as well as for the private life annuities business. For public policy, as well as for the management of financial institutions, it is important to forecast future mortality rates. Standard models for mortality forecasting assume that the force of mortality at age x in calendar year t is of the form exp(αx + βxκt). The log of the time series of age‐specific death rates is thus expressed as the sum of an age‐specific component αx that is independent of time and another component that is the product of a time‐varying parameter κt reflecting the general level of mortality, and an age‐specific component βx that represents how rapidly or slowly mortality at each age varies when the general level of mortality changes. The parameters are usually estimated via singular value decomposition or via maximum likelihood in a binomial or Poisson regression model. This paper demonstrates that it is possible to take into account the overdispersion present in the mortality data by estimating the parameter in a negative binomial regression model. Copyright © 2007 John Wiley & Sons, Ltd.
Designs for Discrimination Between Bivariate Binary Response Models
Authors: Yanagisawa Yukto
Published: May 2007

We propose a test statistic for discrimination between alternative bivariate binary response models and the optimal design procedure which is an extension of T‐optimality. Under certain conditions we prove that the maximum value of the power can be‐obtained when the degrees of freedom of the test statistic is one. The conclusion is the same as that in discrimination between alternative univariate separate models. However the test statistics are different.
A Simple Method to Obtain all the Sample‐Values and their Probabilities of the Wald‐Wolfowitz Test Statistics in the Existence of Ties
Authors: Yassouridis A.
Published: May 2007

In order to carry out non‐conservative tests in the general two‐sample problem with ties, we want to know all possible sample‐values of the used test statistics and their occurrence probabilities as well. But this knowledge can be acquired only after very protracted attempts. In the present paper we depict a simple technique for obtaining that without any exertion in the case of the Wald‐Wolfowitz test statistic. With that, we then are able to lead the Wald‐Wolfowitz test easily and effortlessly in any manner conservative or non‐conservative and in the existence of any number and any length of ties.
A Study of Distribution‐free Tests for Umbrella Alternatives
Authors: Chen Y. I. , Wolfe D. A.
Published: May 2007

In this paper we are concerned with test procedures for umbrella alternatives in the k‐sample location problem. Distribution‐free tests are considered for both cases where the peak of the umbrella is known or unknown. Comparative results of a Monte Carlo power study are presented.
Comparisons of Some Chi‐squared Tests for the Test of Independence in Sparse Two‐Way Contingency Tables
Authors: Lawal H. B. , Uptong G. J. G.
Published: May 2007

We consider in this paper, the behaviour of a class of the CRESSIE READ (1984) power divergence test statistics indexed by parameter λ ‐I(λ), with the modifiedX2test statistics (LU) proposed by LAWAL and UPTON (1984), for sparse contingency tables ranging from the 3×3 to the 10×10. We present a sample of our results here. The results indicate that the LU test out‐performs either the Cressie‐Read suggested testI(2/3) or the Pearson's test ‐I(1). Our results further show that the modification to the likelihood ratio test [Y2=I'(0)] proposed by WILLIAMS (1976) performs like the parentY2test, very poorly compared with either theI(2/3),X2or the LU test statistics.

Power results also indicate that the powers of the LU test are in all cases considered in this study slightly higher than those ofX2andI(2/3) tests. The LU test is therefore strongly recommended for use with sparse two‐way contingency tables because in all of the cases considered, none of the other test statistics consistently out‐performs the LU test with respect to attained α level or power.
Boolean Models: Maximum Likelihood Estimation from Circular Clumps
Authors: Ayala G. , Ferrándiz J. , Montes F.
Published: May 2007

This paper deals with the problem of making inferences on the maximum radius and the intensity of the Poisson point process associated to a Boolean Model of circular primary grains with uniformly distributed random radii. The only sample information used is observed radii of circular clumps (DUPAC, 1980). The behaviour of maximum likelihood estimation has been evaluated by means of Monte Carlo methods.
Choice of Scale and Asymmetric Logistic Models
Authors: Hauck Walter W.
Published: May 2007

In recent years, a number of authors have proposed generalizations to the binomial logistic model. These proposals were motivated, in part, by the claimed inability of the logistic model to fit asymmetric data, that is, data that does not follow a symmetric S‐shaped curve. In this note, it is demonstrated that by changing the scale of the independent variable(s), the logistic model can fit asymmetric data. Logistic models are fit to data from BLISS (1935) that had been used as an example by three of the authors; the logistic models fit Bliss' data as well as the proposed alternative models. In a general sense, these data serve as an example of the need to consider the appropriate choice of scale of the independent variables in logistic analysis.
On the Measure of Agreement Between Two Raters
Authors: Jolayemi E. Tejumola
Published: May 2007

The degree of agreement between two raters is re‐examined. An alternative statistic which uses the chi‐square distribution is proposed. We conclude that this statistic is better than the usual k‐statistic when the classification variable is at least ordinal.
On Edge‐Corrected Kernel‐Based Pair‐Correlation Function Estimators for Point Processes
Authors: Doguwa Sani I.
Published: May 2007

Edge‐corrected kernel‐based estimators are proposed for the pair‐correlation functiong(t). These estimators are compared by simulation methods with the existing edge‐corrected estimator suggested by FIKSEL (1988, Statistics, 19, 67–75). The results of the simulation study suggests that all the edge‐corrected estimators are almost unbiased. Furthermore, the estimators proposed in this paper have a smaller mean squared error than the existing alternative. Finally, the catoptrophorus semipalmatus nesting pattern is explored.
Simultaneous Statistical Inference Concerning the Standardized Mortality Ratios (SMB) of Several Strata in an Epidemiologic Study
Authors: Rao B. Raja , Marsh Gary M.
Published: May 2007

In the present paper, simultaneous prediction intervals are constructed for some mortality measures involving real data in a recent retrospective epidemiologic study of a cohort of man‐made mineral fiber workers. The object is to compare a test population with a standard population in which the workers are exposed to several levels (say K) of a suspected carcinogen and the number of deaths in the K exposure groups are recorded. The SMR is chosen as a mortality measure for this comparison. If the total number of deaths d. in the entire study is known, the number of deaths in the various strata become dependent random variables. Using univariate statistical procedures to test the significance of the individual SMR's is inappropriate and may give misleading conclusions. The present paper shows how to test the simultaneous statistical significance of the SMR's of the K exposure groups, i.e., to test the simultaneous null hypothesis Ho : E(SMR1) = E(SMR2) =…E(SMRk) = 100. If the null hypothesis Ho is rejected, it is shown how to identify the SMR (or the SMR's) which contributed to the rejection of Ho. The power function of such a test is also constructed for some simple and useful alternative hypotheses.
Robustness of the Probability of Correct Selection Against Deviations from the Assumption of a Common Known Variance
Authors: Driessen Stefan , Van Der Laan Paul , Van Putten Brand
Published: May 2007

In this paper we investigate the robustness of the probability of correct selection against departures from the assumption of a common known variance for the Indifference Zone approach (cf. BECHHOFER(1954)), as well as for the Subset Selection approach (cf. GUPTA(1956, 1965)) in the case of Normal populations. It appears that there is a serious lack of robustness in the sense that the actual lower bound of the probability of correct selection can be considerably smaller than the pretended lower boundP*of the probability of correct selection based on the assumption of a common known variance, ifP*is taken 0.75, 0.90, 0.95 and 0.99, respectively.
Sequential Sampling Estimation for Finite Populations ofN = nrObjects
Authors: Arnold B. C. , Groeneveld R. A.
Published: May 2007

Random sampling from a finite population of sizeN = nr(rknown) is considered. The statistic observed isT, the number of observations required until thekth set of sizelfrom thensets ofris obtained. An asymptotically unbiased estimator ofnis obtained together with its approximate variance. Recommendations are made for choices ofrandl, based on the large sample expectation ofT. An application in archeology to the estimation of the number of individuals originally present based on multiple bone counts is considered.
Sampling Methodology for a Boat‐Fishing Survey Design for Hawaii
Authors: Sen A. R.
Published: May 2007

The primary objective of this study is to develop a workable and cost‐effective sampling plan for obtaining reliable estimates of annual catch made by recreational boat‐fishermen in Hawaii and of efforts expended by fishing method for some of the important management species.

Sampling methodology will be developed in an intercept survey through interview of boat fishermen who were intercepted at sampled ports on the island of Oahu for estimating:

(i) number of fishing trips at a particular site or port during a specified time period,

(ii) total catch (weight) and also catch for individual species by fishing method,

(iii) total time spent at sea e.g., boat hours by fishing method.

The sampling strategy will take into account the need to obtain reliable and more specific information to meet particular fisheries management goals. Other research problems which may have important management implications and bearing on the sampling design will also be considered. Finally, sample size will be derived to estimate catch, effort and catch per unit effort at a port with a pre‐assigned level of accuracy.
Further Results on Minimax Designs to Estimate the Slope of a Response Surface
Authors: Huda Shahariar
Published: May 2007

The problem considered is polynomial regression and minimization of the variance of estimated slope maximized over all points in the region of interest when the design region and region of interest are hyperspheres with a common centre. Optimal designs under the criterion are derived for the second‐order model. Method of deriving optimal designs for the third‐order model is indicated and some limiting results on these designs are obtained.
Accuracy of Asymptotic Interval Estimation Methods for Comparing Two Risks
Authors: Nurminen M. , Nurminen T.
Published: May 2007

In 1985, Miettinen and Nurminen proposed asymptotic likelihood‐based methods for the interval estimation of risk differences, risk ratios and risk‐odds ratios. In the present study, with the use of simulated coverage probabilities in small samples, the actual confidence coefficients of all three of the proposed interval estimates for unstratified data were determined in a comparison with the usual ones. Rated against the 95% coverage probability, the likelihood methods that use restricted maximum likelihood estimators accurately attained the nominal level. The recommended limits also apportioned fairly equal error rates for both tails. The customary intervals performed less successfully. For simple risk differences the estimated confidence probabilities failed to reach the 95% level. For the differences in log‐transformed risks, the tail probabilities of the confidence intervals were disparately allocated, and the method was occasionally incomputable. For the difference in logit‐transformed risks, the uncorrected Woolf intervals were at times fallible and somewhat conservative in comparison to the likelihood ratio‐based intervals. Modification of the conservative Cornfield limits for the risk‐odds ratio greatly improved the accuracy of the likelihood score‐based procedure. With sparse‐stratified data the likelihood score approach produced a biased estimate of the risk‐odds ratio, which for matched pairs equals the square of the exact, conditional maximum likelihood estimate.
The Sequential Estimation of Quantal Response Curves for Small Sample Sizes
Authors: Wharton Robert M. , Srinivasan R.
Published: May 2007

An approach to the sequential estimation of the location and scale‐parameters of a logistic response curve using small sample sizes is discussed. The experimental design employed is a variation of Dixon's Up‐Down method with variable step size. Modified maximum likelihood estimates for the location and scale parameters are used in conjunction with this design. The effectiveness of the new estimation procedure and a comparison of this experimental design with some standard alternative designs are examined using Monte Carlo simulation.
A Single Compartment Quantal Response Model with an Inspection Process
Authors: Horng Chia‐Tsung , Huang Wen‐Jang , Lo Huang Mong‐Na
Published: May 2007

In a single compartment quantal response model, besides the input and release processes, an inspection process, assumed to be independent of the input and release processes, is considered. Each time when a release occurs, we assume the amount of release is randomly proportional to the amount present and the proportional rates form a sequence of independent and identically distributed random variables with support on [0, 1]. The input policy we consider is a modification of (s, S) input policy in the inventory model. More precisely, let 0 ≦s2 ≦s1 ≦s ≦ S, if after a release, the amount of the drug in subject's body is less than a level s2 which is small enough, then there will be an input immediately with probability 1 — p and no more inputs thereafter with probability p, also there will be an input immediately if the dose level is in the interval [s2, s1). If the dose level is in the interval [s1, s) there will be no input unless the inspector arrives. On the other hand, if the dose level is greater than or equal to s, then there will be no input. We consider a stochastic model as described above, and obtain the expressions for some quantities of interest. A Monte Carlo study has also been carried out to demonstrate some behaviors of our quantal response process.
On Nonrandom Mating Systems for Attaining Hardy‐Weinberg Equilibrium
Authors: Tai J. J.
Published: May 2007

LI (1988) showed that random mating is a sufficient, not a necessary condition for the Hardy‐Weinberg principle. A nonrandom mating population that behaves like a random mating population is thus called a ‘pseudo‐random mating population’ by him. The pseudo‐random mating system studied by him has been focused on those populations in which the parental generation is in Hardy‐Weinberg proportions. In other words, the mating type frequency deviations from random mating for each parental genotype add up to zero. In this article these restrictions are relaxed and new pseudo‐random mating systems that immediately yield Hardy‐Weinberg offspring are also obtained. This is possible because reciprocal crosses have identical segregation probabilities for an autosomal locus, and the manipulation of the combined frequency of reciprocal crosses does not change the gene frequency of the population. A comparison of these new patterns with that of Li is given in the Discussion.
First Passage Time Models for Prediction of Developmental Stages
Authors: Jensen Jens Erik , Rudemo Mats
Published: May 2007

The problem of predicting the date of a developmental stage for plants or animals is formulated as a first passage time problem for a random process, e.g. accumulated degree‐days. By a suitable embedding in a continuous time model the likelihood becomes a smooth function of the parameters, which may be estimated by use of the maximum likelihood method. A set of data on waiting times from sowing to heading for spring barley is analysed. For data of this type we suggest models with variance components corresponding to stations and years. Modifications to take into account variables in addition to temperature, e.g. day length, soil properties and variety effects are briefly discussed. The transform both sides technique of CARROLL and RUPPERT (1984) is used to stabilize the variance and to achieve approximate normality of the residuals.
On Discrimination of (Stationary) Stochastic Processes
Authors: Wernecke K.‐D. , Kalb G. , Stuerzebecher E.
Published: May 2007

An essential basis of medical diagnosis are biopotentials obtained from the body‐surface of the patients.

If these time‐functions are to serve for computer‐aided diagnostics (using discrimination procedures) the known methods fail because of the existing small sample sizes for a large number of features (amplitudes).

In the paper a method is given allowing discrimination of biopotentials also with such an extreme ratio of the number of features to the sample size.

Furthermore, univariate tests are provided, enabling a decision to be made on whether the possibly arising distinctions may be attached to the mean values and/or the spectra of the underlying potentials.

Clinical applications from the field of otolngical diagnostics demonstrate the usefulness of the described methods and show in particular their superiority compared with the known linear discriminance analysis.
On Analysis of Proportions in Tables with Spoiled Data
Authors: Lachenbruch P. A.
Published: May 2007

This paper discusses analysis of dispersion tests in tables with spoiled data, that is, where some cells are missing. BENNETT (1987) gave a method for estimating the missing cells in a two‐way table and illustrated it with a simple example. This paper uses GLIM to estimate the models and indicates that the General Linear Model performs the computations without need to estimate the missing values. The binomial error model also may be used for this problem, and is the more natural approach to the problem.
Applying Canonical Analysis to a Kind of Generalized Regression
Authors: Liu Chui‐Yu
Published: May 2007

This paper is concerned with the generalized model E(φ(Y)! X) =φ(X) involving the transformations on both the predictor vector X and the response variable Y. For this purpose, Taylor expansions and canonical analysis are applied. For optimizing the expansions, it is shown by a simulation study that not only prediction error, the combination of model error and noise error, is an important index, but the distribution of the residuals and the t‐values of the coefficients also must be considered. Furthermore, the results of penicillin titrition show that the practical situations often need to be considered in selecting an appropriate model for a real‐life problem.