The researchers found that different methods used to analyze US real GDP trends and cycles gave conflicting results, but this was due to overlooking a significant change in the trend in 1973. Once this change was properly considered, all methods showed the same cycle with a non-stochastic trend, except for a few periods around 1973. Their new approach using a mixture of Normal distributions for errors accurately captured business cycles, including level shifts and changes in slope, and aligned well with common understandings of economic cycles.