synthetic cohort effect

[toreilly69]

what is a synthetic cohort effect? an example would be appreciated as well

[Markandshez]

from:
http://www.cdc.gov/nchs/datawh/nchsdefs/synthe ticcohort.htm

hypothetical cohort of persons that is represented when data for a year or other brief period are treated as though they relate to a single cohort. For example, the total fertility rate, which summarizes the age-specific birth rates for a population of women in a given year, may be assumed to represent the average total children born per woman for a synthetic cohort of women that passed through life bearing children at the given rates.