Consideration of cognitive variance components potentially solves Beauchamp’s paradox

Consideration of cognitive variance components potentially solves Beauchamp's paradox.

Beauchamp (1) presents a paradox: There is genetic selection favoring reduced time spent in education, or educational attainment, among the contemporary population of the United States, amounting to an expected decline of 1.5 mo per generation. Despite this finding, the average time spent in education among this population has increased by 24 mo per generation (1). This paradox is analogous to ...

Variance Components

Variance Components

Femoral Components: The French Paradox

It has become generally accepted that the cement surrounding a proximal femoral implant should be not less than 2 mm thick and that it should be complete i.e. without any ‘windows’ in the mantle. The widely used Barrack grading for cementing included no comment on the thickness of the cement mantle on its introduction in 1992 [1]. The following year the ‘A’ grade was qualified by the addition o...

The paradox of cognitive change.

Properties of cognitive change scores were compared in adults over age 70, for whom longitudinal changes are often negative, and in adults in two age groups under age 70, for whom the changes are often close to zero. Longitudinal assessments of three measures of memory and three measures of speed across an average interval of 2.4 years were obtained from a sample of 1,282 healthy adults between...