Joshua's father Jack, who died in 1997, had been a "card-carrying" member of the United Auto Workers. With his father as his role model, Joshua first became interested in unions as a child, and his interest continues to this day. He frequently tracks union trends and developments. Which of the following is incorrect regarding union membership in the United States?

A recent study on union participation rates found a positive correlation between union participation and wage inequality.

Decades ago, when unions were strong and roughly one in three workers were union members, they were able to exert a powerful influence over maintaining high wages.

According to a recent study, the largest factor contributing to union decline has been the growth of jobs outside of traditionally unionized industries.

According to a recent study, even in unionized industries, managers have increasingly grown opposed to union activity.