Counting Observations in Panel Data and filling in missing values

[Christopher Weber]

Hello everyone,
I am new to STATA and have a question regarding the preparation of my Data sample. "PERMCO" shows the respective firm id, "year" shows the year in which an M&A took place. There is two things i want to do with the data:

1.: I would like to count the number of observations for each PERMCO per year, so that at the end, for example, for PERMCO "10078" instead of four times, I have the value "2002" listed there only once, and behind it, in a new variable, information is given about the frequency of the observation 2002.

2.: I would like to add the years missing in the interval 2000-2010 for each PERMCO group. The missing values vary throughout the Dataset and are not the same missing years for every PERMCO. Since no observation has taken place in these missing values, have them output with a number of "0" according to the logic explained in point 1

I kindly ask for your help in creating a code for these concerns.

Original File:



What I would like it to look like (example for PERMCO 10078 representative for the entire data set):




I hope someone can help me. With best regards

Christopher

[Clyde Schechter]

Something like this:

contract PERMNO Year, freq(Numberofmergers)
fillin PERMNO Year
replace Numberofmergers = 0 if _fillin

Note: Code not tested because example data shown was not importable to Stata. Beware of typos or other errors, but this is the gist of it.

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[Christopher Weber]

Thank you very much for the reply. The Code works well. And also thank you for the advice on posting data examples, I will follow them next time!
Best regardsI
Christopher