Effective random seeding of random number generators

To obtain different sequences of values from a random number generating algorithm, we must start with different seed values or discard a variable number of initial samples. For maximum independence among sequences, differences must include the lowest order seed bits, and some generators require one to wait many samples for differences to propagate to the significant bits. While it is straightforward to generate two statistically independent sequences, it is surprisingly difficult to generate three or more such sequences.     

A note on general intelligence and the MA deviation concept

Restraints are imposed on the fullest emergence of g when subjects of equal chronological age are drawn from a restricted range of intelligence, or when groups representing different levels of IQ are factor-analyzed separately. Realistically, persons representing the extremes of intelligence cannot be included in the same study unless they are approximately equated on mental age (MA), in which case the relative performances of the extreme groups can provide useful information about the nature of intelligence. Comparisons of less extreme groups (e.g., average vs intellectually retarded or gifted) are also informative, particularly when attention is given to the types of tasks on which the retarded show the largest MA lag and the gifted show the largest MA acceleration.     

Correlations,contrasts, and components: Fourier analysis in a more familiar terminology

The Fourier transform partitions the energy in a waveform into the sum of the energies of simpler components. This process is the same as the partitioning of variance into linear contrasts and is a way of measuring the correlation between the waveform and each member of a family of prototype model waveforms. Such a partitioning will often, but not always, result in a meaningful decomposition of the original waveform.     

Coping within couples: adjustment two years after forced geographic relocation

Is our understanding of how individuals adjust to stressful life events increased when we analyze their adjustment in ways that recognize that these individuals are also married couples? The data used to answer this question came from a unique “natural experiment” occasioned by the forced evacuation of the Israeli settlement of Ophira under the terms of the Camp David Accords. We found that the adjustment of individuals within couples became more similar across the relocation, that is, couples adapted as a “family system.” This occurred because the coping skills of one member of the couple “drove” the adjustment of both partners.     

Gender differences in health-related quality of life

In 1986 the life expectancy at birth was 71.3 years for males and 78.3 years for females--providing a 7-year advantage for women. Although women live longer, it has been reported that they paradoxically experience more physical and psychological illnesses. In this article, we estimate the expected well-years or quality-adjusted life years for men and women in the general population. The data were obtained in a random sample of 1,034 residents of San Diego. The well-life expectancy uses standard life expectancies with adjustments for quality of life. The well-life expectancy for men was 59.8 years; for women, it was 62.7 years. Thus, the quality adjustment had significantly more impact on women (15.6 years) than on men (11.5 years). Age-specific estimates of health-related quality of life suggested a male advantage before age 45 and a female advantage after age 45. The benefits of well-years of life as a public health statistic are discussed.     

Mentally retarded individuals outperform college graduates in judging the nonconservation of space and perimeter

Most adults of average and superior intelligence incorrectly assume that in a two dimensional figure two attributes, area, and perimeter, are locked in a fixed relationship such that if one remains unchanged so does the other. Consequently, when they correctly conserve one attribute during shape transformation, they incorrectly conserve the other. Mentally retarded individuals assume no such fixed relationship but depend exclusively on perceptual information. Although this dependence adversely effects their judgment of conservation, it allows them to correctly judge the changed state of the nonconserved attribute.     

Tower of Hanoi performance of retarded young adults and nonretarded children as a function of solution length and goal state

Three experiments were conducted with the Tower of Hanoi task to assess problem solving ability in 6-, 7-, 8-, and 10-year-old nonretarded children and mentally retarded young adults of varying maturational ages. In Experiment 1 we gradually reduced the number of moves required for solution until subjects could solve the 3-disk tower-ending problem. Although all groups experienced difficulty with the standard 7-move problem, all but the trainable retarded group readily solved the 6-move problem. The trainable group did not reach a comparable level of success until the 4-move problem. On the 7-move problem the retarded groups performed at the level of nonretarded groups that were maturationally $\text{1}\text{1}\text{2}$ to 3 years younger. An analysis of first moves indicated that subject groups differed in the strategies they used to solve the problems. In Experiment 2, practice effects were ruled out as a source of the superior performance on the 6- than on the 7-move problem. In Experiment 3, 7- and 10-year-old nonretarded children and mentally retarded young adults did not differ on 5-move problems in which configuration of the goal states was varied. A comparison of all 5-move problems judged to have the same depth of search requirements indicated that the tower-ending problems were significantly easier to solve than the partial-tower-ending problems, which in turn were easier than the flat-ending problems. A limited depth of search capacity sets boundaries on the use of sophisticated strategies and, to a large extent, accounts for the retarded groups' maturational lag.     

Clock-driven FORTRAN task scheduling in a multiprogramming environment

The existing ISA-standard FORTRAN task-scheduling calls require careful programming to provide timing accuracy even in a single-user system, and do not explicitly provide a mechanism for resolving task conflicts in a multiprogramming system. A simple assignment of priorities to tasks can guarantee timing accuracy to one task, but the risks generating maximum, unnecessary interference with other tasks. An alternative to such a standard priority scheme, not known to be available on common commercial systems, guarantees timing for one task while minimizing interference among tasks.