Figure 3
The graph displays a time series plot labeled “C U S U M squared”. The horizontal axis is labeled “year” and ranges from 1997 to 2023. The vertical axis is labeled “C U S U M squared” and ranges approximately from 0 to 1. A line with circular markers represents the C U S U M squared values over time. Two straight boundary lines are shown above and below the main line, forming upper and lower limits. From 1997 to around 2005, the values remain close to 0 with a gradual increase. Between 2005 and 2010, the values rise slowly to approximately 0.2. From 2010 to around 2015, the line increases to around 0.4. After 2015, the values rise sharply to approximately 0.8–0.9 by around 2017. From 2017 to 2023, the line levels off near 1. Throughout the time span, the line remains within the upper and lower boundary lines and does not cross them.Results of cumulative sum (CUSUM) Test. Source(s): Author’s computation using Stata 17