Can a generation be Defined?

Can we really define a generation? What of the challenge in representing all aspects of what defined a generation.
"Generational analysis has a long and distinguished place in social science, and we cast our lot with those scholars who believe it is not only possible, but often highly illuminating, to search for the unique and distinctive characteristics of any given group.But we also know this is not an exact science. We are mindful that there are as many differences in attitudes, values, behaviors, and lifestyles within a generation as there are between generations. But we believe this reality does not diminish the value of generational analysis; it merely adds to its richness and complexity."(Wikipedia)