The Equivalence of Parameter Estimates from Growth Curve Models and Seemingly Unrelated Regression Models

Seemingly unrelated regression models and growth curve models are examples of multivariate models that require special estimation techniques. Parameters in seemingly unrelated regression models can be estimated by using two-stage Aitken estimation based on unrestricted residuals; parameters in growth curve models can be estimated by using a Potthoff-Roy (1964) transformation based on an estimate of the dispersion. With proper choice of the seemingly unrelated regression model, the two multivariate models and corresponding parameter estimates are shown to be equivalent. Recognition of the equivalence simplifies the presentation of these more complicated multivariate models. The connection is also of interest for more flexible growth curve models.     

Not Such Strange Bedfellows After All

Abstract

The irritable bowel syndrome (IBS) is best defined as abdominal pain of greater than three months duration, with or without a change in bowel habits. Barium studies, sedimentation rate, and the lactose tolerance test are usually within normal limits. The underlying physiology includes a predominance of 3 cycles/minute basal electrical rhythm (BER). The abdominal pain is poorly localized and usually intermittent, without a clear relationship to medication. Differential diagnosis should include inflammatory bowel disease, infectious colitis or gastroenteritis, lactose intolerance, gallbladder disease, peptic ulcer disease, pelvic inflammatory disease, ovarian cysts and tumors, and endometriosis. A sedimentation rate is an important part of the diagnostic workup which may or may not include barium studies. Anticholinergics have been shown to alter the abnormal BER of irritable bowel syndrome and have proven to be of use in treating this syndrome. Dietary counseling should include advising the patient to eat slowly and at regular hours, and heat applied to the abdomen in the form of a hot water bag has been useful. “Overprogrammed” individuals with irritable bowel syndrome should be advised to modify their activities as this type of stress may give rise to the symptoms.

“Effect of Estrogen/Progestin Potency on Lipid/Lipoprotein Cholesterol,” PATRICIA WAHL, CAROLYN WALDEN, ROBERT KNOPP, JOANNE HOOVER, ROBERT WALLACE, GERARDO HEISS, and BASH RIFKIND. We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P < 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Envoid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives. (New England Journal of Medicine 1983;308:862–7.)     

Straw men and fairy tales: Evaluating reactions to a natural history of rape

In this paper we respond to two frequent criticisms of our book, A Natural History of Rape (Thornhill & Palmer, 2000). The first criticism portrays the book as little more than a “just‐so” story that human rape is an adaptation. We demonstrate that this portrayal is not accurate. The second criticism reflects a common response to the book's challenge of the popular assertion that rapists are not motivated by sexual desire but instead commit these crimes motivated by the urge to power, domination, and violence, and the urge to degrade and humiliate women. We demonstrate that such criticisms of our book are inherently contradictory and illogical. We believe it is important for sex researchers to understand that these sorts of criticisms are seriously flawed so that future research efforts toward understanding the causes of sexual coercion are not stalled.     

Naturalistic Observations of Peer Interventions in Bullying

This study examined peer intervention in bullying using naturalistic observations on school playgrounds. The sample comprised 58 children (37 boys and 21 girls) in Grades 1 to 6 who were observed to intervene in bullying. Peers were present during 88% of bullying episodes and intervened in 19%. In 47% of the episodes, peers intervened aggressively. Interventions directed toward the bully were more likely to be aggressive, whereas interventions directed toward the victim or the bully-victim dyad were more likely to be nonaggressive. The majority (57%) of interventions were effective in stopping bullying. Boys were more likely to intervene when the bully and victim were male and girls when the bully and victim were female. The implications for anti-bullying interventions are discussed.     

Relations of Parent–Youth Interactive Exchanges to Adolescent Socioemotional Development

This study examined the relations of parent–youth agreement and disagreement during a joint problem-solving task and multi-methodological indices of socioemotional outcomes in adolescents (mean age  =  13). One hundred and sixty-seven parents and their adolescent children participated. Each parent–youth pair played the interactive game 'Jenga', and their interactions were analyzed for frequency of elaborations (agreement during three or more conversational turns) and negotiations (disagreement during three or more conversational turns). Elaborations during parent–youth interactions were related to less negative classroom behavior, better self-regulation, and more task persistence in youth. Findings are discussed in light of the importance of parent–youth interaction and youth autonomy in adolescent socioemotional development.     

Advocacy and the SSSP: An analysis of research articles in social problems

This study examines the extent of advocacy in the research articles appearing in the journalSocial Problems from 1953–1992. The Society for the Study of Social Problems (SSSP) was founded in order to counter the mainstream scientism of the American Sociological Society. Becker’s presidential address to the SSSP in 1966 confronted the issue of advocacy and the consequences associated with research that does not explicitly “take sides.” The present study investigates advocacy inSocial Problems by means of a typology drawn from Becker’s address. The findings indicate that political advocacy has increased sharply over the duration ofSocial Problems. Implications of the findings are discussed in the context of value-neutrality and its relation to social problems research.