ITSA error message in time series: _t already defined

[Alexandre Bugelli]

Hi all, maybe it,S a little silly question, but i’m new in Time Series and Stata. I used a dataset for panel data and I want to confirm results by interrupted time series using the same data set. Basically I count on 26 states, 12 periods (2004 to 2015), and a balanced set, counting a total of 312 observations. The variable I used is the infant mortality rate (IMR) of all states with treatment period starting in 2010. I used the single unit model and as I mentioned trying to evaluate the possibility of any change in IMR trende after treatment. I used these codes do set data to time series, which worked fine in my first try. I wrote codes to set data and run itsa for a specific state (id = 20) as follows;

Code do set data: . tsset id t (id = state code, 1...26 and t = years, 2004...2015)

Code to run itsa: . itsa imr, single treatid(20) trperiod(2010) lag(1) posttrend figure

As I said, it came up with results which unfortunately I cleared before saving, and now when I try to run the same code I receive the error message “_t already defined”.
I do not understand why these codes worke properly and now, even if I start all over, it shows this message over and over.
Someone may halp me to fix this.

Thank you all.

[Brian Brosmer]

itsa imr, single treatid(20) trperiod(2010) lag(1) posttrend figure replace

See

help itsa

replace replaces variables created by itsa if they already exist. If prefix() is specified, only variables created by itsa with the same prefix will be replaced.

[Alexandre Bugelli]

Hi Brian,

thank you for your promptly reply. It works now. I am used to panel data commends, which there is no need to replace variables.