Behavioral geneticists commonly parameterize a genetic or environmental covariance matrix as the product of a lower diagonal matrix postmultiplied by its transpose-a technique commonly referred to as "fitting a Cholesky." Here, simulations demonstrate that this procedure is sometimes valid, but at other times: (1) may not produce fit statistics that are distributed as a chi2; or (2) if the dist...

The purpose of the study was to determine how often Maryland judges agreed with the opinions of forensic evaluators in deciding whether to transfer youthful defendants to juvenile court from adult court and to investigate which factors were most important in the opinions of the evaluators and the final decisions of the judges. Data were extracted from a sample of 200 waiver evaluations, and cas...

Epidemiology is the study of how often diseases occur in different groups of people and why.1 Cancer epidemiology is therefore the study of how often cancer occurs in different groups and why. Part of the work on examining why is to measure the effect of factors which may put a patient at high risk of getting the type of cancer in question. The first section of this review looks at epidemiologi...

Mazur’s theorem states that there are exactly 15 possibilities for the torsion subgroup of an elliptic curve over the rational numbers. We determine how often each of these groups actually occurs. Precisely, if G is one of these 15 groups, we show that the number of elliptic curves up to height X whose torsion subgroup is isomorphic to G is on the order of X, for some number d = d(G) which we c...

This paper summarizes a natural resource damage assessment for the State of Montana. Mining wastes have caused significant reductions in trout stocks in a 145-mile stretch of Montana's Silver Bow Creek and Clark Fork River. To estimate economic damages from decreases in catch rates, we develop and estimate an individual-based utility-theoretic model of where and how often an angler will fish as...

In an effort to contribute information on the relationship between time perspective and academic outcomes, we examined the frequency with which adolescents’ reported thinking about the past, the present, and the future in relation to self-reported grade point average. Analyses of questions that assessed how often (i.e., never, monthly, weekly, and daily) adolescents thought about the past, the ...

OBJECTIVE: US parents were surveyed to determine the amount of background television that their children are exposed to as well as to isolate demographic factors associated with increased exposure to background television. After this, we ask how certain home media practices are linked to children’s background television exposure. METHODS: US parents/caregivers (N = 1454) with 1 child between th...