Levinson arrived at his account on the basis of a series of intense individual interviews with a group of American men in mid-life.
Although they came from a variety of backgrounds and had a range of careers and family histories, similar patterns appeared to emerge.
Although Levinson’s original sample was relatively limited, subsequent work has shown that the model fits many American women reasonably well,
too (Levinson, 1996;Roberts & Newton, 1987).