Hello everyone,

I am doing my thesis which seeks to find the variables that influence the survival of micro-enterprises in the 2015-2021 period, for this I have an unbalanced panel database that includes variables that vary over time, for example, I have the GDP by state that varies over time (that is, one value for 2015, another for 2016, etc), my question is, to estimate a Cox model, should I specify to stata that I’m using variables that change over time? I have read about it and I know that the extended Cox model exists, but I'm not sure that this extension of the model refers to these types of variables that change over time.
I also have another question: should I specify the ID variable for multiple records to the model or is it not necessary?


Thank you,
Ana