The study looked at economic data from 10 industrialized countries to see if business cycles are different during recessions and expansions. They found that during recessions, the economy tends to have larger negative movements than during expansions. This suggests that industrialized economies naturally have uneven business cycles. The study also found that the estimated output gap is closely related to future output growth, unemployment rates, and capacity utilization. In many cases, the relationship between these factors follows a specific pattern called a convex Phillips Curve. The researchers used a model that combines different forecasts to estimate the output gap, which was found to be reliable and only needed small adjustments over time.