05-14-2017 05:15 PM
This is the sitaution:
I have time series (daily readings), which can trend downwards. I would like to introduce a dichotomous dummy variable that indicates when the time series contains a trough (dummy=1) or not (dummy=0). A trough occurs if the current time series is n% (e.g. 80%) below past values but future values go up again to 100% relative to the current value.
I was told that I can use the chow test to create these dummy variables. I have no SAS/ETS and wonder if I can use the chow test in datasteps to create the dummy variable. Any pointers would be very much appreciated. Thanks!