Hi, I have a question about an exercise we did in my econometrics class. I have this database of teachers and schools of about 62,000 observations, and I'm asked to use the collapse command to count how many schools and how many teachers there are, but when I collapse (count) teacher_id school_id and then list , the result is more than 60 thousand in each of the variables. Now, I know that it is not the result since for each school there must be a certain number of teachers. I've been searching the forums and I see that some people use the command to generate a gen=cons constant but I don't really know how to use it. So if anyone knows or wants to contribute something, I would greatly appreciate it.