10 The following pattern occurred in a census of Lower Potomack Hundred, Frederick County, Md., 1776: A ratio of 1.0 is age-neutral; the proportion who rounded their ages down and those who rounded up were precisely the same. Lower ratios are biased toward youth; higher ones are biased toward age:

Image

Reported Ages

Backcountry Age Bias (1776)

Modern U.S. Age Bias (1950)

19-21

1.00

1.04

29-31

.67

.94

39-41

.83

.93

49-51

.53

.93

59-61

1.50

.92

Computed from data in Gaius M. Brumbaugh, ed., Maryland Records (2 vols., Baltimore, 1915, rpt. 1967), 181-92. Onomastic evidence indicates that a large proportion of this hundred were from North Britain; 20th-century data is from Ansley J. Coale and Melvin Zelnik, New Estimates of Fertility and Population in the United States (Princeton, 1963), 127-29.