ITSA trperiod help

[Zaina Kahiel]

I'm trying to run an interrupted time series analysis and I ran the following code:

I want my intervention to start on April 23 2020

tsset Date, daily

Output: time variable: Date, 31mar2020 to 30may2020
delta: 1 day


Code for ITSA:

itsa dayaverageallltc, single trperiod(23apr2020) lag(1) posttrend figure
output: r(121) : trperiod() invalid -- invalid numlist

Can someone help me figure out the formatting for the date?

Thank you!

[William Lisowski]

The authors of itsa (a community contributed command available from SSC) chose the easy way in their documentation and used yearly data, where the Stata Internal Format value for, for example, the year 1990 is just the number 1990. For daily dates, you need to use the function td() to conveniently provide the Stata Internal Format value of the daily date.

. display td(23apr2020)
22028

. display %td 22028
23apr2020

So one approach to this command would be

itsa dayaverageallltc, single trperiod(22028) lag(1) posttrend figure

but a more readable version would be

itsa dayaverageallltc, single trperiod(`=td(23apr2020)') lag(1) posttrend figure

[Zaina Kahiel]

Thank you! This worked

[Jane Quan]

Hi，
I am using ITSA (Linden, 2015) command on my monthly data.
and I used following command before I using "tsset":
"gen mdate1=monthly(mdate, "YM")
format mdate1 % tm".

well, now I can run one intervention with code "itsa logim, single treat(13) trperiod(2017m1) lag(1) posttrend figure"
but if I use one more intervention time point as the guide shows " itsa logim, single treat(13) trperiod(2017m1 2019m1) lag(1) replace posttr figure"
the result shows " m(2017m12019m1) invalid, r(198);"

I don't know what went wrong here.

Thanks.

[Jane Quan]

Hi，
I am using ITSA (Linden, 2015) command on my monthly data.
and I used following command before I using "tsset":
"gen mdate1=monthly(mdate, "YM")
format mdate1 % tm".

well, now I can run one intervention with code "itsa logim, single treat(13) trperiod(2017m1) lag(1) posttrend figure"
but if I use one more intervention time point as the guide shows " itsa logim, single treat(13) trperiod(2017m1 2019m1) lag(1) replace posttr figure"
the result shows " m(2017m12019m1) invalid, r(198);"

I don't know what went wrong here.

Thanks.

Well，for my question, the answer is to add an semicolon, which are not introduced in the pdf manual but you can find it with command help ITSA.