The article "Output Fluctuations in the United States: What Has Changed Since the Early 1980's?" by McConnell and Perez-Quiros explores how economic output in the US has changed over time. The researchers analyzed data from the early 1980s to understand how fluctuations in output have evolved. They found that since the early 1980s, the US economy has experienced smaller and less frequent fluctuations in output compared to previous decades. This suggests that the US economy has become more stable over time.