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"The study included 69,744 women and 1,429 men."

Does this mean it's much easier to find optimistic women than men?

"Data are from 2 cohorts, women from the Nurses’ Health Study (NHS) and men from the Veterans Affairs Normative Aging Study (NAS)"

Probably easier to find women still alive at that age. (Here in the U.S. at least, women tend to outlive men by ~5 years)

If women are more optimistic than men, then that alone could be sufficient to yield the results of the study (correlation).