Age and Variability in Francis Galton's Data

Abstract

Between 1888 and 1894, Francis Galton collected measurements from more than 7,500 people of all ages, including some in their 80s. Regression analysis of age on relative variability measured by the coefficient of variability performed on measures of 8 dynamic characteristics (grip strength [right, left], visual [right, left] and auditory threshold, vital capacity, and reaction time [sight, sound]) revealed an increase in variability of performance of men and women for auditory threshold only, contrary to the general claim that variability increases with age. Analysis of variance did, however, show the pattern of decline in the means of performance of these measurements. This pattern appears to characterize contemporary cross-sectional data sets spanning several decades. Although caution regarding conclusions is recommended because of the limitations of the group sampled, the results provide further reason to investigate the limitations of the general statement that variability increases with age.