02-18-2016 11:28 AM
I have annual time series data for 63 years (attached). The data demonstrates a U shaped curve. I am trying to estimate the Unobserved Components Model with spline regression.
the command I use is
proc ucm data=land; id year interval = year; model es; irregular; level; slope; splinereg annual KNOTS=1958 1962 1977 variance=0 noest; estimate; run;
However the Spline terms are not significant. is there any other method to incorporate a U shaped trend in PROC.
My data is attached below. Kindly let me know what I am doing wrong